You can use the sheet music as a reference and enter the chords into the BB grid. As far as entering the melody, I think the quickest way to do that would be to actually play the part in using midi and your keyboard. You can then simply use a VST- plug in synth to provide the audio for the melody.

Of course, you can also grab the midi file ( if it exists ) for the song from an online midi song site and just use GM to play the parts which should include the melody.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.