[OT] radius, pam and ts

Hi, to everyone. I know this is an OT post but i don't know where post. I have a freeradius server that's work fine. I have a tslp that's work fine (with passwd user) (it's and ubuntu 8.04 with ltsp correctly installed) Now I want use freeradius to autenticate user in tslp desktop. So, I think to install http://freeradius.org/pam_radius_auth but no request is sent to freeradius server. The questions: 1. where install pam_radius_auth? In /etc or in /opt/ltsp/i386/etc? 2. how to configure for ltsp? Thanks in advance v.