Homer.
I have used the vice method on several rims with good success. You have to be sure that the unbent side is sitting flat against the vice and then push directly on the bent up area. Otherwise you may bend both sides. Like David said, it is easy to bend it where you don't want to. I use a press with a special fixture, but a vise will work if you are careful.
You can also lay the rim against a heavy table with the tire removed. Lay the bent area on the edge of the table at the proper angle with the bent area facing up and smack it with a soft, dead-blow hammer. I use a lead hammer. You can't buy a lead hammer anymore, you have to make them. You can use a regular hammer, but be sure to place a peice of wood or something soft in between the hammer and rim.
The every three spoke method of truing that Elk mentioned is a good one. :thumb:
Take your time and press it a little at a time. You don't want to go too far because it is very hard to unbend them.
Just my $ .02