Is there a way to get Screamer 4x4 to run in a window in Windows 7? For the game, the exe I'm running is "Screamer4x4_gl.exe". Is that the OpenGL version?

I don't see an option in the game's menu to select windowed mode. Is there a way to set this manually?

The game has no windowed mode, but you can use D3D Windower to get around that:

The following page has both a download link, and a link to an article which tells you how to use it:
http://community.pcgamingwiki.com/files/file/129-d3dwindower/