You need the ip address of saurik's server (Cydia server) in order to set up the redirect. The IP address is 188.8.131.52 and place the address in front of gs.apple.com
TinyUmbrella can also modify your host file for you (along with caching your SHSH blobs!)
Edit: gs.apple.com works fine for restoring to current FW if you don't need unlock. I still would recommend backing up SHSH with TinyUmbrella.