We had a Shark with 96MB working once, using a 64MB double-height
DIMM module we got at Fry's and one of the regular 32MB modules.
Im fairly sure the hardware is ok if you find 2 bank 64MB modules, but
(as someone pointed out) you need the correct revision of the Firmware
to detect and map it in.

See also
http://www.research.digital.com/SRC/iag/info/dnaext/dnard/info/sdram.html
which has some other details.
If you still want more details details read the comments in:
http://www.research.digital.com/SRC/iag/info/dnaext/dnard/pal
(REV4 and REV5 have the same PAL, so use the REV4 defines)

Mark