I am tired of Karaoke style backing tracks and want to replace the guitar in a song that I already have. Can I do this with software?
If you know the name of the song, search the web for MIDI files. Under success, you can open MIDI file with some even free tool like MuseScore and remove unwanted staffs. The rest can be played by MuseScore directly or you can also export and burn CD.
There have been many sites which claim to "phase out" the instrument, but there are always those transients in the background like cymbals still lingering around. Jammit has licensed the original backing tracks from the labels so you can mute or isolate the part you want to learn. Hope this helps you!