This is already possible through the Global hotkeys plug-in. The buttons on the remote are considered to be regular keypresses by windows. Therefore you can just add a Global hotkey to the buttons of the remote, the exact same way you add when you add hotkeys to the buttons of your keyboard.
Hit Ctrl + P, go to General Preferences > Global Hotkeys (assuming you have it installed). Enable it if it is disabled. Select the action "Playback: Play/pause" click in the hotkey field (the field with the red circle around it in the attached image) and hit the play/pause button on the remote. Then just hit the add button, and you should be good to go.
That was a great tip, thanks! however, now when I have winamp open, my volume up and volume down buttons don't work on the keyboard. When I turn winamp off though, they start working again. Any suggestions?
In newer versions of winamp to get my windows media center remote to work I simply go to Winamp Preferences [Ctrl + P] and then Global Hotkeys and then check the Enable default multimedia key support... and my remote works great!