Make sure AvP2 is updated to the latest version, which is currently: 126.96.36.199
Place the di.rez file in your 'c:\AliensVsPredator2' folder.
Start the game; and in the Game Launcher's Main Menu select 'Options'.
Enter (copy & paste, if you like) into the 'Command-Line' field: -rez di.rez
Check the box marked "Always specify these command-line parameters" to always load the map.
Return to the Game Launcher's Main Menu and select: 'Play'. The game will then start with new map components loaded.