This is controlled in conf/HTTPStreamers.xml. The RequestFilters for the HTTP Streamers are executed first. You will need to disable these to intercept these requests. You can turn off HTTP Streams by removing them from the HTTPStreamerAdapters list in conf/VHost.xml:
Why don't you do all of this outside of Wowza. Have the inital request from the GSS device go to a web browser that redirects to Wowza. So the web server is doing all the redirect and not Wowza. Always send the initial request from the load balancer to the web server.