I've managed to create a PKGBUILD for XBMC, hope it works for you. I set up distcc controlled by my raspberry booted with the 224-start.elf, and it managed to compile, but it did take some hours. In order to do the final linking and compression, swap was needed.
An older pkg build using the PKGBUILD below can be found here
The PKGBUILD can be fuond in the AUR
EDIT: updated dependencies
EDIT2: bumped to new git version, added pkg link
EDIT3-4: Overwrite local CFLAGS to armv6
EDIT5: bumped to new git version, updated pkg link
EDIT6: linked to AUR PKGBUILD