Just to spread some KISS :-)
Compiling a debian RT kernel is quite straightforward.
Download debian sources or vanilla ones from
kernel.orgPatch according to your release (
http://www.kernel.org/pub/linux/kernel/projects/rt/ )
Run `make oldconfig` inside the sources dir, you will probably be asked about configs in the newer kernel not found in .config-YOUR_RUNNING_KERNEL
Then follow the common workflow, run `make menuconfig`, at least change only the PREEMPT opt and seti it to 'complete preemption'.
Create your linux-image debian package with make-kpkg (
http://www.debian.org/releases/stable/i386/ch08s06.html.en)
If your running kernel works this one will too 99.9%
my 0.02€
regards
-r