I want a button to send a message when it is left clicked as well as right clicked

Ok, so I've decided to enter the world of Cocoa, and I've decided to start off by doing my favorite little project: Minesweeper clone. So I've got my preliminary classes all worked out, and now I just need to get my interface down. 

I need each little button to send a message when it is right clicked, and a different message when it is left clicked. My first guess would be to extend NSButton or something, but I can't seem to find any way to differentiate the two mouse buttons.