actually, xport's emulators do support command line rom launching.
I'm not sure how successfully it's been done though. It all depends on your dash's ability to launch with a command line option, and then the emulator's ability to pick up that parameter and load the rom.
Do a search for "command line" and see what comes up.
I believe XBMC just added an execute function which I'm going to have to investigate a bit. This has been one of my back burner things to do for awhile now.
This did help. <