Go either to a local music store or e-bay and pick up a used 3/4 violin. Should be able to get one for between $50 to $75, with case, bow and a stick of rosen. Get it tuned right by a competent music shop. There are Beau Coup violin learning sites on the web, including MIDI fake books with every fiddle tune you could ever imagine. Have him review the 3 left hand positions and how to hold the bow. Put him in a room by himself and let him start sawing away. Don't help him until he ask. You might be really surprised how fast he picks it up. It's up to you and the rest of the poor souls in the house to ignore the cat under the rocking chair.
JB
I gave my dad a violin for Christmas, one we had to fix up. My son helped, and was fascinated by it. He had to carry it everywhere we went, and every chance he got he would open it and make that screaming cat, which dont bother me at all. So I agree, a fiddle may be in the future. Will go along with his screaming coyote sax.