I’ve got ScummVMDS on my R4 card, and it’s really easy to set up and use. It does play some old Sierra games, but by old that means REALLY old – only the AGI games. The interface is a bit difficult on the DS, since tapping keys with the stick is much much slower than actually typing on a keyboard, but it’s still nice to have the games on a handheld device anyhow. The Lucasarts games are great, though. Only one hasn’t worked right for me so far and that was Indiana Jones and the Last Crusade.
Now, speaking of AGI Sierra games, I’m DYING to get my hands on that rare AGI version of KQ4 to put on this thing, but of course I can’t find it anywhere. The SCI version won’t work, unfortunately.