This is the boblight addon for using the open source ambilight clone ( http://code.google.com/p/boblight/ ) from within XBMC.

For accessing the settings during video playback just put the file script.xbmc.boblight.keymap.xml into your "userdata/keymaps" folder. 

You can access the settings during playback by hitting the key "b" or "B". (Note: a former keymapping to that key will be overwritten by this keymap file. If there is a 
conflict you just can change the mapped key to something else).

For this addon to be working you need a library for communicating with the boblightd - daemon. For linux you need to compile it on your own:

Linux:
goto the projects site http://code.google.com/p/boblight/ and download the source code. Then compile and install the library by issueing the following commands (without the $'s):

$ cd <source of boblight>
$ ./configure --without-portaudio --without-ffmpeg --prefix=/usr
$ make && sudo make install

This will install the libboblight.so library into /usr/lib - where the boblight addon will find it