This is how you detect a Ctrl+Z:
$(document).keydown(function(e){
if( e.which === 90 && e.ctrlKey){
alert("yahoo!");
// Do your stuff
}
});
jQuery has some built in stuff as well:
Demo: http://jsfiddle.net/
Article: http://www.mkyong.com/jquery/how-to-detect-copy-paste-and-cut-behavior-with-jquery/