mschap surpport pam_radius

Now I am set up a System like pam_radius--->FreeRadius--->JRadius,and it is working.But the problem is the Pam_radius_auth.so send the radius packet use pap. I need it work with MSCHAP or eap, how can I do? I see your reply in mailinglist page that "See rlm_mschap in FreeRADIUS, and port the code to pam_radius".But I am sorry ,I can`t really catch it. Please tell me the process step by step . Thanks!