hardware - How can I make the button on my headphones control something other than the stock music player?

When I press this button, it plays/pauses the stock music player. I don't use the stock music player--I use a comination of Last.fm, Grooveshark, and Winamp. I would like to make the button play/pause whichever player I am currently using. If this isn't possible, I would like it to simply control Winamp, instead of the default player.

I am using Android 2.1 (unrooted) on a Samsung Fascinate.