Hi,
I spent some time to understand howto change the audio track in the AVI movie with more then one audio tracks during Xine playback. The short key - + and - work on the standalone Xine and doesn't work under LinuxMCE. However, the DCE router command can be used for that:
/usr/pluto/bin/MessageSend localhost 0 23 1 140 5 "<audio track number>" 41 ""
where audio track number is the track number, i.e. 0 (default one), 1, 2 etc. Sure it'd be nice to add it to the LMCE GUI menu. Because I'm not sure that it'd be possible to do that for LIRC.