What can I say, my first kernel compile/update was a success.
Well, my second, to be exact, 'cause I used the config file from current as titopoquito suggested and compiled again.
Also I used the rc.modules from ftp://slackware.mirrors.tds.net/pub/...rent/source/k/
and changed the name of the kernel from "bzImage" to "vmlinuz-generic-smp-18.104.22.168-smp", I think that is rather irrelevant, just thought I'd mention it.
And now my wlan adapter shows up with "iwconfig" with the b43 drivers loaded, the reason I went through this in the first place.
Thanks to everyone who took the time to reply!