I think for paste-events you'll need jQuery. For everythink else (like onkeypress) you could use an ordinary a4j:support.
<a4j:support event="onkeyup" oncomplete="console.log(this); console.log(event);"></a4j:support>
Thank you for your reply christian,
I thought that an "onrender" event should solve my problem with a4j:support. But i couldnt.