[Coco] SuperIDE Quesion

[Joe]

Hi,
I'm trying to set up a 256 Meg CF card for both Nitros9 and HDB-Dos. So this is what I did
run IDEPROBE LBA size is 500976 Sectors (wrote it down)
run "wizard" total sectors 500976 etc
told it I wanted 256 Dos disk
Offset for Nitros9 was 679392 (told to write this down for nitros9 so I did)
About 170 Meg so that seems right 256Meg minus 80Meg  for HDB

saved the final version and ran flash to block 0
moved MPI selector to slot 3 and restarted
HDB dos comes up and 256 disks are seen (so far so good)
Back to MPI slot 4
insert Superdriver disk and DOS
Nitros9 boots 
did a dmode /i0 and see typ is 0x91 set it to 0x81 (Bit 4 off no autodetect)
Now how do I tell format to only use up to block 679392??
at this point if I do a format /i0 I get Disk capacity: 260,096 Sectors (about 66Meg) to small
Do I HAVE to specify C/H/S or will it take LBA? Where do I use the 679392 I dutifully wrote down??
Thanks for any help.