Assuming that you have the video out plug on your snes you can do it. but you need media center to set the output to composite in (it will detect it when you plug the short dongle in). power cinema also works with that card but it sucks
that said. it's not a good idea to run a game through a tv tuner card, because they max out at 29fps. games of course go faster.
use a snes simulator instead. google is your friend