Found this on the internet for ya:
1) Get some heavy twine; the kind the post office sells.
2) Wet the boots with mink oil or lether balm - you want to soften the outer shell without distorting or damaging the leather.
3) Wrap the still-moistened boots up in an old toel or bedsheet. Secure the cloth with twine.
4) Strike the boots repeatedly with a heavy rubber mallet, sledgehammer, or large rock. Be sure there's only enough cloth around the boots to prevent scuffing.
5) Untie twine and extract the boots. Wipe off any remaining oil/balm.
6) Scrunch the boots up, in such a way that the toe end curls back toward the upper laces. It'll take time and a fair amount of effort, at first, but it'll get easier. Cover with cloth again and retwine as best as possible. Use c-clamps of a wood vice, if available. Again, be sure to place a soft cloth between the clamps and the boots.
7) Strike again with mallet, making sure this time to use softer blows.
8) Untie/unclamp. Test-fit boots for comfort.
9) Repeat steps 2-onward, until desired effect is attained.