OK, here's the non-internet way to do it.
1. Designate one of your PCs as "The Server"
2. On the server machine, install the Windows component "Dial Up Server"
3. On the client machine, create a new Dial Up Networking connection with the phone number of the server machine guy's modem.
4. On the server machine, start the Dial Up Server. Setup passwords etc.
5. On the client machine, run the connection to dial the server machine.
6. Once connected, run UT on the server machine and "Start New Multiplayer game". Set everything up as you would for a LAN game but don't select "Optomize for LAN". Start the game.
7. On the client machine, run UT and select "Find LAN games". The server should appear on the list.
Happy fraggin!