The UCLX issues isn't actually opcode or alignment related as was first suspected (could have been for all I know.. the stub is written in ARM assembler which I haven't felt the need to learn yet).
The issue is actually related to the size of /dev/shm to which /tmp is linked (/dev/shm/tmp). By default this is 1m in size making the upper limit on /tmp 1m. This isn't even close to big enough to allow the UCLX stub to decompress these files.
I'm going to set this size to 10m for the next Cacko3K release. Note that the memory isn't used until the space is used in the tmpfs. 10m we know to be a good figure, that's what Cacko 1.22 uses and we don't see any complaints about it being too big on that.
For the people interested in changing it in the meantime they should note that it's not enough to change /etc/fstab and reboot. The mount actually comes from one of several potential lines in /root/etc/rc.d/rc.rofilesys. Look for lines like...
mount -t tmpfs -o size=1m none /dev/shm
Note that there are three lines that potentially mount tmpfs so I would suggest modifying them all, I haven't worked out which one is the normal one. Just hacked the change from 1m to 10m in this line and rebooted.
Note also that /root is on the read only flash file system (/) so to be able to change this you first need to...
mount -o remount,rw /dev/root /
Once you have made the change simply reboot and you have up to 10m for /tmp. Most UCLX binaries should work now.