Pass cleartext-password to exec module with EAP

Hi! I need to use an external script to check both username and password. We don't have the cleartext version of these passwords, which are encrypted in a Postresql database... Although I'm running into troubles with the configuration files... And there's one major issue I can't seem to solve : EAP. I don't know how to pass the cleartext version of the entered password to the external script from the inner-tunnel of the EAP process. Could anybody help me on this? Thanks!