To do this you first need to go to the Android market and install two free applications, first is the Download Crutch, what this does is fool your phone into thinking that there is an application in place that uses the file type that contains the ROM, which is the game you are downloading.
Second you download SNesoid Lite, it is free, there is a full version, but I do not know what the advantages of it are. The SNESOID is an emulator that runs the ROM to play the game.
From here you can go to www.theoldcomputer.com, and then on the left hand side select Roms, then scroll down and select Super Entertainment System (SNES), this will give you the list of downloadable ROMS, click the one you would like to play, it will download.
From here launch the SNesoid App, it will say that No ROM is loaded, press your menu button, open, and then under sdcard/download should be all of the ROMS that you have downloaded, I have been succesfull at downloading and playing Super Mario World, and Mortal Kombat II. So give it a try.
With this however I have not been able to figure out all of the keys for both games, if you download and figure out what key performs what action please post to the forum so we can determine the layout.