<< flash bios.... >>
probably cant do that on a 486..
anyhow.. i had this program called ontrack disk manager that was a drive overlay program..
it let me use a 3gb drive in a 286 (dont even ask why i put a 3gb drive in a 286)
im not sure if its free or not though, i think i got it from seagate's site, but that version would only work with seagate drives. so if you can find a program like that or similar, you should be able to use 8gb, im not sure about 20gb though.
look around on maxtor's site, there might be something that will work there