Overriding Defailt Refresh rates

I’m trying to override the default refresh rates under OPENGL for a fixed frequency monitor. The monitor can only handle a refresh of 120Hz at 800x600 and beyond. Is there a variable or registry hack that can change the OPENGL default of 60Hz to 120Hz? Are there game specific commands known to anyone such as for the Unreal and Quake engines?

Thanks in advance…