Form Validation callbacks in a Module.

Hello, I was wondering if a solution was found for using form validation callbacks in modules, as discussed in .(JavaScript must be enabled to view this email address).

The issue lies in checking if the callback method exists:

// Call the function that corresponds to the rule
if ($callback === TRUE)
{    
   if ( ! method_exists($this->CI, $rule))

Where is this actually checking? the CI super object? if so then where should I put the callback?

I think this is a biggie. I dont want to hack EE core files, is there perhaps a way I could extend the EE_form_validation class (which is already extending the CI_form_validation class) in a module library?