I've ran into the same (or rather very similar) problems. My solution is to build my own SDK without scratchbox using an armel debootstrap of Lenny and mixing in the maemo repositories. It seems to work so far and runs (chrooted) both nativley on the n900 and on my PC (Squeeze) with qemu.

I'd have to do it a few more times to get the instructions in order, but if anyone would like to try I can post what I have so far...