[Users] distributed setup

Hi, I have an OpenSER DISPATCHER instance successfully forwarding requests to one of four OpenSER "worker" instances. I need to authorize by originating IP on the worker machines but of course requests are only coming from the dispatcher machine. I had thought of having the dispatcher drop the originating IP in the headers but haven't been able to figure out how to do that. Something like append_hf( "origin: $si\r\n" );? I had also thought about having the dispatcher send back a 302 Moved Temporarily but can't figure out how to get at the dispatched IP. Is there a better way to be doing this short of checking for the IP on the dispatcher? I had hoped to avoid that in favor of having the dispatcher handle extreme load. Thanks. -Anders