Starting X (KDE) from chroot possible?

[Frank <hugelmopf@web.de>]

(I hope nobody is going to complain, that this question involves the word 
"Ubuntu". The question is not directly related to that.)

I decided to install an (K)ubuntu chroot on my Debian AMD64 system, because 
that solves two issues for me:
- the few 32bit-only applications can be run (flash, OOo, ...)
- Kubuntu has the most recent KDE beta/RC packages, so I can test them and 
find show stoppers

Since my experiences with an Etch chroot showed everything is pretty easy, I 
was confident that running the whole X server from within the chroot should 
be possible. So I installed everything in the chroot, and it works as 
expected, but as soon as I try to start an X server from the chroot via 
"startx", it fails.

First it behaves normal, i.e. like switching to the X display, but before the 
typical X background would appear, it turns black and stays like that. I can 
not even switch back to the console anymore, have to do a hard reboot.
The Xorg.log can be found here:
http://hugelmopf.ohost.de/paste/Xorg.0.log

This is the first time I try to start an X server from the chroot, because I 
want to try the KDE 3.5 RC1 packages, which I have installed in the chroot.
Does anybody have an idea, what I need to get this running?
Do I have to "bind" anything from the host system to the chroot?

Thanks a lot,
Frank