OK..... got a working kernel driver from

http://packages.debian.org/unstable/graphics/device3dfx-source

And I've got it compiled and loaded... but I have no idea what to make for a UDEV rule. 

I tried this for a UDEV rule: 

DRIVER=="3dfx", KERNEL=="3dfx", NAME=="3dfx", MODE="0666", SYMLINK+="voodoo2"

But it doesn't work

[root@greystar ~]# udevtest /module/3dfx
main: looking at device '/module/3dfx' from subsystem 'module'
udev_rules_get_run: rule applied, '3dfx' is ignored
udev_device_event: device event will be ignored