Cross site form validation using JSONP

[eluser]Unknown[/eluser]
Hello,

I am doing some cross site form processing using ajax/jsonp. Because I need a response for server side validation I am using jsonp which forces me to use $_GET or parse_url($_SERVER['REQUEST_URI']) in this case to get the form values.

My question: Is it possible to use the built in form_validation library and callback functionality by manually passing variables instead of the normal $_POST data?

thanks