After digging endlessly this night I finally found the solution. The short answer is that you can use the disks' GUIDs (which persist even after disconnecting a drive) with the zpool command.

Long answer: I got the disk's GUID using the zdb command which gave me the following output

root@zeus:/dev# zdb
hermes:
    version: 28
    name: 'hermes'
    state: 0
    txg: 162804
    pool_guid: 14829240649900366534
    hostname: 'zeus'
    vdev_children: 1
    vdev_tree:
        type: 'root'
        id: 0
        guid: 14829240649900366534
        children[0]:
            type: 'raidz'
            id: 0
            guid: 5355850150368902284
            nparity: 1
            metaslab_array: 31
            metaslab_shift: 32
            ashift: 9
            asize: 791588896768
            is_log: 0
            create_txg: 4
            children[0]:
                type: 'disk'
                id: 0
                guid: 11426107064765252810
                path: '/dev/disk/by-id/ata-ST3300620A_5QF0MJFP-part2'
                phys_path: '/dev/gptid/73b31683-537f-11e2-bad7-50465d4eb8b0'
                whole_disk: 1
                create_txg: 4
            children[1]:
                type: 'disk'
                id: 1
                guid: 15935140517898495532
                path: '/dev/disk/by-id/ata-ST3300831A_5NF0552X-part2'
                phys_path: '/dev/gptid/746c949a-537f-11e2-bad7-50465d4eb8b0'
                whole_disk: 1
                create_txg: 4
            children[2]:
                type: 'disk'
                id: 2
                guid: 7183706725091321492
                path: '/dev/disk/by-id/ata-ST3200822A_5LJ1CHMS-part2'
                phys_path: '/dev/gptid/7541115a-537f-11e2-bad7-50465d4eb8b0'
                whole_disk: 1
                create_txg: 4
            children[3]:
                type: 'disk'
                id: 3
                guid: 17196042497722925662
                path: '/dev/disk/by-id/ata-ST3200822A_3LJ0189C-part2'
                phys_path: '/dev/gptid/760a94ee-537f-11e2-bad7-50465d4eb8b0'
                whole_disk: 1
                create_txg: 4
    features_for_read:

The GUID I was looking for is 15935140517898495532 which enabled me to do

root@zeus:/dev# zpool offline hermes 15935140517898495532
root@zeus:/dev# zpool status
  pool: hermes
 state: DEGRADED
status: One or more devices has been taken offline by the administrator.
        Sufficient replicas exist for the pool to continue functioning in a
        degraded state.
action: Online the device using 'zpool online' or replace the device with
        'zpool replace'.
  scan: scrub repaired 0 in 2h4m with 0 errors on Sun Jun  9 00:28:24 2013
config:

        NAME                         STATE     READ WRITE CKSUM
        hermes                       DEGRADED     0     0     0
          raidz1-0                   DEGRADED     0     0     0
            ata-ST3300620A_5QF0MJFP  ONLINE       0     0     0
            ata-ST3300831A_5NF0552X  OFFLINE      0     0     0
            ata-ST3200822A_5LJ1CHMS  ONLINE       0     0     0
            ata-ST3200822A_3LJ0189C  ONLINE       0     0     0

errors: No known data errors

and then

root@zeus:/dev# zpool replace hermes 15935140517898495532 /dev/disk/by-id/ata-ST3500320AS_9QM03ATQ
root@zeus:/dev# zpool status
  pool: hermes
 state: DEGRADED
status: One or more devices is currently being resilvered.  The pool will
        continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
  scan: resilver in progress since Sun Jun  9 01:44:36 2013
    408M scanned out of 419G at 20,4M/s, 5h50m to go
    101M resilvered, 0,10% done
config:

        NAME                            STATE     READ WRITE CKSUM
        hermes                          DEGRADED     0     0     0
          raidz1-0                      DEGRADED     0     0     0
            ata-ST3300620A_5QF0MJFP     ONLINE       0     0     0
            replacing-1                 OFFLINE      0     0     0
              ata-ST3300831A_5NF0552X   OFFLINE      0     0     0
              ata-ST3500320AS_9QM03ATQ  ONLINE       0     0     0  (resilvering)
            ata-ST3200822A_5LJ1CHMS     ONLINE       0     0     0
            ata-ST3200822A_3LJ0189C     ONLINE       0     0     0

errors: No known data errors

After resilvering had been completed everything worked well again. It would have been nice to include this information, that you can use a disk's GUID obtained through zdb with the zpool command, with the manpage of zpool.

Edit

As pointed out by durval below the zdb command may not output anything. Then you may try to use

zdb -l /dev/<name-of-device>

to explicitly list information about the device (even if it already is missing from the system).

There's no difference between the options when all is said and done — drives are interchangeable. "Just add sdi as the new spare" requires fewer steps and minimizes the amount of time that you spend in a resyncing state, so it's the natural choice.

In order to use again the same drive in ZFS, if you are sure the disk is not faulty, doing DD to the first 10 GB of the drive is a good start, but you need to do it also at the end of the drive. But there is no need to DD 10 GB, I believe the first and last MB is enough.

I solved it this way:

dd bs=512 if=/dev/zero of=/dev/sdk count=2048 seek=$(($(blockdev --getsz /dev/sdk) - 2048))
dd bs=512 if=/dev/zero of=/dev/sdk count=2048 

Then just add the "new" disk back to the ZFS pool. No need to labelclear, scrub, wipe the disk. DD is all you need. You also should not partition the disk after DD. ZFS will not accept any previously partitioned disk.

Then just zpool replace <pool-name> <old-device> <new-device>

normally is the disk-by-id and is the device listed in lsblk.

why don't you just use zpool replace as suggested on the screen? replace the faulty drive with the new one and let zfs create the partitions and resilver the drive? maybe I didn't get the question, sorry

export the pool and import it with zpool import -d /dev/disk/by-id/ instead. If using an sdX name is all that was wrong, it should find the correct disk and use that.

Depending on how quickly you replaced the drive after removing it, the kernel may have assigned a new drive letter to the drive. Look in your dmesg to see which letter it got, and use that for the last argument in 'zpool replace'. Going forward, I'd recommend using by-path or by-vdev for the naming of your drives, so you can have a fixed naming for the slot that the drive is in. Unlike the /dev/sdX entries, these are stable across reboots, and make it much easier to find the position of a failed drive.

Apologies if I'm not following quite correctly. You're saying you have a single-disk zpool and it's come up with errors? To replace it you should be able to plug in your new one and run zpool replace poolname badDisk newDisk just fine? Rather than trying to destroy the pool and starting again. Though if it's getting some serious IO errors it may be too late to replace. It's also worth noting that if you have plenty of RAM for ZFS's ARC feature... a cache SSD probably isn't gonna be too much more helpful than just using ARC. That said, if you're talking about an ssd LOG device (not CACHE) SLOG's are more for PROTECTION for incomplete disk transactions than 'speedups' for pool writes. Would you mind providing us with the output of zpool status and dmesg from this machine? It helps the community find problems very well.

To replace a failed disk with a hot spare, you do not need to zpool replace at all (and in fact this might cause you all sorts of grief later; I've never done this). Instead you are supposed to simply zpool detach the failed disk and the hot spare automatically replaces it.

If you have failing drives, I would not attempt to replace them one-by-one. Buy a new disk shelf, build a new pool with the new disks and copy your data over ONCE.