From a debian install, select "shell access" (or something similar). You can then search /etc/lib/modules/2.6.8-i386/kernel/drivers/scsi for your required driver and insmod it if it exists then do a "detect hardware" again.

On the other hand: I recently had issues with an old delledge server with an addon percraid 2/dc that required the old megaraid driver. Damned if ubuntu didn't just pick it up. As it turned out, I was able to insmod the driver in a pure debian install as above once I realised that it was included but not being automatically detected.