Way to use AJAX for reading/writing to list in context of Site Definition?

Question

I'm deploying a subsite to multiple SharePoint site collections which has a voting aspect based on Lists.

I'm trying to keep vote fraud to a minimum by attaching identity to a vote.

I can use UpdatePanels to handle the clicks and assign identity server side to complete this, but AJAX would be far better.

I'm having trouble deploying either a Web Service or an HttpHandler in a site definition. What would be the best way to make this work?