Some notes on building XBMC from source on the Raspberry Pi: I started with the Raspbian 2013-09-25-wheezy image from here. After basic setup, I switched to CLI only, set the GPU memory to 16 MB, logged in over SSH, and started a screen session. A remote session is preferred, since there will be a lot of coping back and forth between the RPi and your desktop.
For the most, I followed these instructions, with a few modifications: First, the boot files to set GPU memory are not there in the Raspbian distribution I had installed. Instead, I used raspi-config to set the memory split. Secondly, the large one-liner apt-get install of all the dev packages (step 4 in the instructions) did not work very well. It gave dependency conflicts with the mesa packages. I found myself splitting up that line into many chunks, which then worked fine. Finally, a few packages were missing, and I had to run configure several times to figure that out. In the end, I also installed these:
apt-get install dh-autoreconf gawk gperf zip ccache
For a successful build, I had to modify the search path of a header file. There are a few ways to go about that, as discussed here. I used this solution:
sudo sed -i 's/#include "vchost_config.h"/#include "linux\/vchost_config.h"/' /usr/include/interface/vmcs_host/vcgencmd.h
That took me as far as a working XBMC setup, however videos are not playing. With MPlayer there is no problem, but XBMC just gives a black screen. I will have to investigate further.
There's a similar set of instructions here.