Sorry Tonja - that was just my sense of humor - I'm a SysAdmin so of course its warped.
I haven't done the kernel patching in Debian.
Looking at the following link:
http://packages.debian.org/unstable/...-debian-2.6.12
I see the following description:
Package: linux-patch-debian-2.6.12 (2.6.12-3)
Debian patches to version 2.6.12 of the Linux kernel
"This package includes the patches used to produce the prepackaged linux-source-2.6.12 package, as well as architecture-specific patches. Note that these patches do NOT apply against a pristine Linux 2.6.12 kernel but only against the kernel tarball linux-source-2.6.12_2.6.12.orig.tar.gz from the Debian archive. . This packages is produced using an updated kernel packaging system and replaces older kernel-source packages"
Since they're calling them tarballs I suspect you download and gunzip/untar it into same directory as your kernel source then do the compile from there. I've not done the source compile on Debian so can't be sure. Perhaps the tarball contains a README that would explain it - you might try doing gunzip/tar tvf on it to see then just extract the README.