I just installed Kalyway 10.5.1 (dual-boot with XP -- that was a pain). It can be tough if you don't do things exactly right. My advice: download and burn a GParted Live CD. It will help you set partitions active quickly when you are having boot trouble.
I believe there might be a new driver out there for the Intel, but I'm not sure. I have the Atheros (Thinkpad a/b/g) and it works with an updated IO80211 kext. From what I've read the ethernet is not doable yet. I also don't have sound working yet but I should soon.
You will also need a Natit.kext for the x3100 graphics that someone has posted here.
My steps for X61s:
1) Install Kalyway with EFI 8 option.
2) Reboot with DVD and go into Utilities / Terminal
3) Make sure vanilla kernel is being used (verify with filesize)
4) Copy in Natit.kext from thumbrive.
5) Remove AppleIntelIntegratedFramebuffer.kext
6) Copy in IO80221 kext (for the Atheros)
7) Delete Extensions cache
Reboot without DVD
That said, I'm sure you know this not the kind of thing that is conducive to step-by-step instructions. Spending some time at the OSX86 forums is helpful to get a lay of the land for when things go wrong (and they will).