how to encrypting accounting?

Hello, yesterday I successful installed freeswitch 1.0.6 with mod_radius_cdr accounting on a remote freeradius 2.1.9 server, freeswitch use freeradius-client 1.1.6 library. I am looking for a way to TLS encrypt accounting messages between Freeswitch and remote Freeradius, actually I can do only clear text accounting with simple shared key auth. Is there a way using configurations files to setup TLS accounting? Do I need to code a bit with freeradius-client library? I keep trying, for the moment many thanks, cheers, Fabio