I'm using XBMC 9.04.1 with both 12.2 and 13.0. I'm using larryhaja's build script. Be sure to build and install the six packages upon which XBMC is dependent. Slackware 13.0 provides some of those packages but not all. Slackware 12.2 needs all six packages built and installed.
Versio 9.04.1 is relatively stable but I can get the app to crash repeatedly when I play certain AVI videos and then stop the video anywhere in midstream. XBMC is an app that is updated at a very fast pace. Unless you want to be a full-fledged alpha and beta tester, posting questions to the forum typically results in a demand for a lot of information, including logs. I've been content to live with some of the nuisances and bugs until the next official release.