When I go to KDE Control Panel -> Ineternet & Network -> Network Settings and enable a NIC, the device is automatically disabled. I press 'enable device', and a second later the device disabled itself. I've got the NICs set up in such a way that they should be working -- the drivers are installed correctly.

I'm rather net to KDE, and I've never had to do anything outside of gnome before. However, I don't really have the time to get gnome up and working. Is there a way to enabling the cards from the command line, or stop kde from auto-disabling them? I usually use ifup, but slackware seems to think the command doesn't exist.

Try runningThere is more here.
Good luck. ;-)