please download the javascript shortcut on :
http://www.openjs.com/scripts/events/keyboard_shortcuts/shortcut.js

put the javascript on your web2py static js folder.
then start to custom your layout.html

Note :
- please change Ctrl+F12 with your custom keyboard shortcut
- please change the action (windows.open) with your desire javascript action

views/layout.html
 

<script src="{{=URL('static','js/shortcut.js')}}"></script>
<script>
shortcut.add("Ctrl+F12",function() {
	window.open("{{=URL('default', 'index') }}", "_self");
});
</script>