Hi everyone,
This night I tried to build QEMU in scratchbox. For the i386 architecture, I had to download the sources of the 2.6.21.7 linux kernel and use its headers as the linux headers (mv /usr/include/linux /usr/include/linux.old && ln -s /usr/src/linux/include/linux /usr/include/linux), because the default headers don't work...
With the ARMEL architecture, I had to do the same thing, but I had also to edit a bit the configure script to make QEMU builds (else it won't recognize the CPU) :
configure : Line 38 : Replace "armv*b" by "arm".

Finally, it worked, and the result is here.

To use it, untar it in '/', QEMU will be located at /opt/qemu/bin/qemu.
In /opt/qemu/share/qemu/afdbd.ima, you will find an old tiny FreeDOS bootdisk I made some years ago (don't try to load the mouse driver with it because it will crash QEMU) ; to use it, type that in a console :
And then open a VNC Viewer (I used vncviewer for maemo on the tablet) and point it to 127.0.0.1.

You will notify it will be slower than every computer you ever seen. When you connect to the VNC server, wait about five minutes to see a cursor, and then you will see the screen slowly filling with characters...

This port is quick and dirty, you have seen it, but as it isn't really useful, it's just for trying and removing ;-)

EDIT : Photo of my N800 running QEMU and vncviewer | Video of QEMU slowly printing the characters...