Kernel (cross-building)
$ make -f debian/rules clean
$ make -f debian/rules source-all
$ fakeroot make -f debian/rules.gen binary-arch_armel_none_s3c24xx
Kernel udebs (cross-building)
When you're done compiling the kernel, you have to build kernel udebs.
$ cd /path/to/d-i/packages/kernel/
$ mkdir armel
$ dpkg -x /path/to/linux-image-2.6.3?-?-s3c24xx_2.6.3?-*_armel.deb
$ cd linux-kernel-di-armel-2.6
$ kernel-wedge gen-deps armel-s3c24xx > ../armel/lib/modules/2.6.3?-s3c24xx/modules.dep
$ kernel-wedge build-arch armel
Now, you should have kernel udebs in the parent directory.
Other udebs
Rebuild (using dpkg-buildpackage or debuild) the various changed udebs (base-installer, ...) and include them in your path/to/d-i/installer/build/localudebs and/or on your repo.
$ mkdir ~/incoming/
$ cd /path/to/d-i/installer/packages/
$ cd flash-kernel && debuild -uc -us && cd .. && mv *.*deb ~/incoming
$ cd base-installer && debuild -uc -us && cd .. && mv *.*deb ~/incoming
$ cd hw-detect && debuild -uc -us && cd .. && mv *.*deb ~/incoming
$ cd libdebian-installer && autoreconf -i -v && debuild -uc -us && cd .. && mv *.*deb ~/incoming
$ cd partman/partman-auto && debuild -uc -us && cd .. && mv *.*deb ~/incoming && cd ..
$ # For some reason, I had to rebuild installation-locale too
$ cd installation-locale && debuild -uc -us && cd .. && mv *.*deb ~/incoming
Debian installer
Now, it's time to build a Debian Installer image for the FreeRunner:
$ cd /path/to/d-i/installer/
$ make build_s3c24xx_network-console
$ # You can build the g-i image too
$ make build_s3c24xx_netboot-gtk
The resulting files should be in dest/s3c24xx/network-console/gta02/