> Is there documentation in a convienet form somewhere that would tell
> me what command I need to boot off of the SCSI disk with ID 5?  `boot
> DKA0' works to boot off the first disk with the firmware on the
> machine I have.

It probably depends upon what particular platform you are using.

For the modern machines, try doing a "show dev" at the >>> prompt.  
I think that lists all the devices you can boot from.  One column 
will have the obvious magic word to use with the boot command. 

My guess would be DKA500