Jack Benny practiced his for all of his 39 years, and never mastered it.
(Actually, I've heard that he was able to play the thing if he wanted.)
Anyhow, I can't help you. I think that, if you want to just fiddle around, you can probably scratch out a tune with not too much practice, but I've never tried it.
Perhaps one of our resident violinists can help.
As for me, I've always wanted to play the organ, but I have too much respect for the instrument to insult it by trying!