oil it up good and put it in a ziplock bag. Lay it on your car dash when it's parked in the sun and leave it for about 1 1/2 hours. Then go play catch with it.......wait, that's how some break in a ball glove.
I'll bet it would work on most any leather.
No one asked (when has that ever shut me up
) but here's how I break in a ball glove:
soak it in a 5 gal bucket of warm water for about an hour. wring it out and stretch the pocket, pound your pocket and then put a ball in it deeply. tie it tight using something that wont cut into the leather and leave marks. I use a folded plastic t shirt bag. then just forget about it for about 96 hours. Should be dry or near dry when you start massaging shaving cream with lanolin into the leather. Do this twice and then every couple days for about a week. Should use about a half a can of red Barbasol. Lastly, massage in some good hand lotion like Gold Bond. Do this and a board stiff glove will play like a 10 season everyday mitt.