Changing beagle board C4 resolution

I just bought the ultimate gadget pack from liquidware and they didn't
have any touchscreens so they sent me the rest of the kit while those
are on back order. The problem is I can't connect the beagleboard up
to a regular LCD monitor without getting an "out of range" message.
I've tried to change the resolution via dvimode in uboot but I guess
I'm just not smart enough. Can anyone help me? It's a C4 board.