Wrote a script to handle patching between the main and -ac trees. It's options are pretty straight-forward:

Generate a shell script that will update me to 2.4.12-ac1: kupi.pl -ug update_me.sh 2.4.12-ac1
Patch up to the latest ac-series patch, then compile and install the kernel: kupi.pl -ai
You'll need to make some changes to the base configuration to get it working on your system, but the Kupi tarball is available here.

Oh yeah, here's a list of ways to say "Oh my god! There's an axe in my head" in various languages.