The gametype_prefabs.zip file you have requested: Tools and Utilities / Mapping Tools / Gametype Prefabs - 289.45kb is not available. Perhaps try browsing all files for the game Call of Duty: United Offensive and upload any files you want to share or are missing. This is the only information we could locate:
Here's a great package for CoDUO mappers by FireBall1. Included are prefabs and tutorials that should help you make your map compatible with Retrieval, Search and Destroy, Base Assault, Capture the Flag, and Domination.