urc separates av receiver codes into several different codesets.  you will have to add multiple devices to the remote in order to them them all on there.   then you can create blank devices and alias the commands you need from each codeset.

here are the codes you want to use

Main:  1238
Main Ext:  1239  (this is the codeset that has the surround modes)
Tuner: 1240
USB/Net:  1242