APT sources for DRI:
deb http://dri.freedesktop.org/~daenzer/debian/dri-trunk-sid/ ./

packages:
drm-trunk-module-src
xserver-xfree86-dri-trunk
xlibmesa-gl1-dri-trunk

Note: you will need to recompile the drm-trunk-module-src with make-kpkg. There’s really no way around it, sorry.