OK... because 800 in 9.XX was introduced to LVM and in HFS format allowed up to I think 16 partitions.. and commands differed.. Only I know (more) 800 using 9.04 (I started with 8.XX) (sic) but did work with a 715,710,725(9.05)...
So I can remember, what commands are you actually passing, what were the ones that worked ( and what for...) that arent anymore? From what I remember its not just adding a new disk of XGB and it works!
The exact model has to be known by the OS, it should have a description in /etc/disktab
id not you would to have to add an entry...
Then you used mediainit command (but was that for 800 only?)
I cant remember of a "format" command

You will maybe need to refresh my memory a bit... but remember you had to use mkdev ( and config -a) and mknod