How do I use OpenGL for games that don't have it as an option?

This one game has Direct3D, 3dfxGlide, and like 5 other things but it doesn't have a place to let me choose OpenGL (which my crappy video card seems to only work with). So I wonder if anyone knows how I could make it add OpenGL to the list. (The game runs under the Unreal Engine)

At least Unreal Tournament has OpenGL support. If I remember right was it neccessary to select "show all" or similar to be able to use it.