Did you google this mate? I just did, and from what I have read its available on cydia.
Snes4iphone requires you to add the roms files to /var/mobile/Media/ROMs/SNES/
After you have added the roms to the above path they will showup insider the Snes Emulator under Browse Tab. There are some added features under options, that lets you choose the skin, toggle scaling on or off, Autosave, Transparency, Framerate Counter and SpeedHacks. (We recommend not enabling SpeedHacks unless you have compatibility issues).
I just checked, and its on several repos on cydia.
I had this a while ago, there was a full version on sinfuliphone. Once you load up the emulator there is an option to add roms and it links you to a working rom site. Never had a problem with it but was good few months ago now, could of changed by now