I grabbed some patches from http://patchwork.ozlabs.org/linuxppc/list to put together a first
efika-patches-2.6.23. It applies and compiles. If you're curious if it actually works as well, well so am I. Feel free to try. I'll give it a try later, but since I've managed to damage my efika, I can't test the ata part and who knows what else is fooked.
efika-2.6.23.tar.bz2 is the compiled kernel + modules and the kernel config file used. That kernel contains the pax and grsecurity patches for 2.6.23 too btw, so don't be suprised if your log files fill up with grsec messages ;-p