Hotkey for custom button

any ideas?

As usual, I have found the solution myself, which might help somebody.
Basically, I attached a keydown event to the iframe created by ckeditor:

iframes = document.getElementsByTagName("iframe");
iframes[0].contentWindow.document.body.attachEvent("onkeydown", catchKeyDown);

then I have to write the javascript function catchKeyDown which handles keydown event of the iframe in the outer aspx page.

var key = 0;
function catchKeyDown (e) {
if (e.keyCode == 17) {
key++;
}
if (e.keyCode == 83 && key == 1) {
key++;
}
if (e.keyCode != 17 && e.keyCode != 83) {
key = 0;
}
if (key == 2) {
key = 0;
CKEDITOR.instances.editor1.execCommand('searcher');
}
}

This sample traps CTRL+S key stroke and when it finds it, it executes the command defined for that custom button.