PAM modules

Hi, Did there anyone who developped a PAM module that operate with radius server? my question is : 1- How does that work ?does it only allow configuration of predefined methodes or could we also programme new PAM module for new/customized authentication methode such as OTP (One Time Password) authentication? 2- could we programme PAM that redirect multiplle authentication requests to different servers and make an "AND" of the received reponses ? 3- how does it work with radius? thanks in advance. Ouahiba.