I have some unused cards of that antique type and I wanted to put a couple of them on an old pc running slackware. I've done some research and finally got it working:

- Go into PC bios setup and mark as "Reserved" some IRQ, I used IRQ 10.
- edit lilo.conf (or whatever you use to pass kernel parametes at boottime) and add in the corresponding section:
append = " ether=10,0x310,4,0x3c509,eth1"

where: 10 is the IRQ reserved before
0x310 is the IO base address to use
4 is the transceiver type (utp)
0x3c509 is to identify the card
eth1 is the network interface name to use

adjust all of them as needed

(take a look at /usr/src/linux-(your kernel version)/Documentation/networking/3c509.txt)

- edit /etc/rc.d/rc.modules and uncomment the line:
/sbin/modprobe 3c509

- power down, plug the card, power up

Hope this will be of help to anyone!
Thanks linuxquestions!