TURN it's an extension of STUN, so TURN server has also STUN features.
https://code.google.com/p/rfc5766-turn-server/ works also as a STUN, so you can try to write something like this:
var pc_config = {"iceServers": [{"url":"turn:my_username@<turn_server_ip_address>", "credential":"my_password"}]};
pc_new = new webkitRTCPeerConnection(pc_config);