JSF 1.2 checkbox How to get instant response?

I have a column of checkboxes and I want to get this effect that when you select 3 of them the rest of checkboxes disables. I've tried everything but I can't make it to do it instantly after clicking on a checkbox (it happens when I reload a page). Every response for that problem is using <f:ajax> but I'm using JSF 1.2 (and I can't use JSF 2 in this project). Is there any way to get through my problem?

Thanks in advance!