Just tried the boot again with no success.
I tried the probe-scsi command to make sure that I was trying to boot from the right partition but it complained and error'd until I restarted the box.
Anyway, I tried to the following command:
OK> boot disk2:0
Then a few minutes later it compained heavily. I couldn't catch all the information because I was on the console but it said stuff like:
"cannot assemble drivers for root"
"trying to mount vfs"
"kernel panic" - followed by lots of numbers...
I'm surprised that it mentioned vfs because I thought I was using ufs...