send variable to form_validation.php or append rules from controller to config file

Hi.

i dont know if it is possible but here we go.

I have some custom validation rules to send a variable as a parameter, everything is fine there. What I wish is to be able to add this validation to my config / form_validation.php rules but... here's the problem.. i think this is not possible...or i'm wrong??

i want send a variable to mi array of rules from controller to config/form_validation.php or append rules from my controller to my form_validation.php

Thanks for your help.