You could make a mouseover theme that could make a dcop call to gaim to minimize or something probably. I don't see why not. If you wanted to do it a different way, ie coding it without superkaramba, you may want to check out xmms-weasel. It does some auto hiding stuff that's pretty cool. Install it and see what I mean. Or even check out the demo movie on their site.
http://xmms-weasel.sourceforge.net/
Really though to embed a window in a superkaramba theme is not possible that I'm aware of. Calling to a window via dcop calls in a superkaramba theme is done in many places. I wonder if you could construct a call to "move" windows. I know that if you open up kdcop, a dcop browser, you can see all the available functions for a specific window. At least for Konsole, you can access it's move() function.
This could end up pretty cool depending on what you do with this.
Good luck!
-Ryan