Custom OSX output resolutions?

I've got an monitor with a resolution of 1920x1200 at 60Hz connected up to my MBP running Snow Leopard. The laptop will only output at a maximum of 1920x1024 at 60Hz. (through a mini display port adapter and a VGA cable)

Currently, the image is output, but its stretching it vertically, which I find horrible to look at.

I'm assuming theres something out there that can create custom resolutions in OSX but i havent found anything yet.
Whats the best way to do it?

Cheers