The main trick here is really just sorting out the build environment. I've only done it for N900 but the guide is there for N8x0's Diablo:
http://maemo.org/development/sdks/maemo_4-1-2_diablo/
I'm a little worried about installing it on my box since I don't want to accidently trash my N900 development environment (it's not obviously that they will play nicely together) but someone with a clean machine might have some luck.