Actually you can use Retroarch with Openelec and play emulated games directly from Openelec and XBMC.
I have it installed and it works like a charm. The only issue I found was everytime you start a game, you have to configure your controller. Maybe there’s a way to get around this, but I still haven’t found it.
I also have build my Hyperion ambilight set with a USBTV007 EasyCAP capturing my TV output. I want it to capture also the Retroarch but I don’t know what is the priority given to Retroarch for the v4l driver. Can anyone help me?