It sounds like the same problem I'm having, except that my card is an IBM CB EtherJet + 56K modem. I recognize that you don't have that card from the Manufacturer ID (unless they've changed it.)
I don't remember the specifics on what I did to make the card work (it's been about 6 months since I "upgraded"). Although I do remember having 0.91g from Donald Becker and using something in the 3.0.x series. (That's before clients/tulip_cb.c appeared and instead was named clients/tulip.c).
I'm interested in what you find out and/or helping if possible.