There is also some very useful information about what you are trying to do on this blog post: http://blog.galemin.com/2011/04/li-5m03-camera-on-beagleboard-xm/
Anyway, the drivers that you need are here: https://github.com/Aptina/BeagleBoard-xM/tree/master/MT9P031/Angstrom they need to be compiled and loaded onto the SD card.
WAIT: this is even better: http://blog.galemin.com/2012/03/buildroot-2012-02-for-beagleboard-xm-with-li-5m03-mt9p031-camera-support/