Get the audio output on your SNES and get an adapter to plug it into the audio in on your computer. I can't remember the SNES outputs though.
OR you could just find a midi online... they are everywhere.
None are more hopelessly enslaved than those who falsely believe they are free.
Quote by Jiro from GLAY
Ner Ive tried, this ones impossible to find.

Tell us what song and we will try to help you.

vgmusic.com has a huge collection of midis, unless you really need the original one.
SNES cartridges have .SPC for sound files. google those along with a game title and you'll find em.

you'll need an SPC player to listen to them tho. (SNESamp i think)
Grammar and spelling omitted as an exercise for the reader.
Oh, it's a ROM, right. Then get Audacity, set it to record your soundcard, and just play what you want recorded.
Thanks guy I figured it out, I dumped the .spc then convertered it into a midi.

However when I play the midi on wmp it sounds fine, but when I port it to GP5 one part doesnt sound right. What other program can I use to play the midi, i.e. show me the notes?