Кажется достаточно обычных keydown и keyup
$(function(){
var mode = "none";
$(document).keydown(function(event) {
//console.log("keydown", event.keyCode);
if(event.keyCode == 17)
{
mode = "ctrl";
}
}).keyup(function(event)
{
//console.log("keyup", event.keyCode);
if(event.keyCode == 17)
{
mode = "not_ctrl";
}
});
$(document).click(function(){
//console.log(mode);
alert(mode)
});
});