None of the non-PC programmable URC remotes (like your MX-500) have much in the way of discretes. The only way to get discretes into the MX-500 is to learn them from another remote that has them. The cheapest way to do that is with a One for All remote. You shouldn't need JP1 as most Sony discretes are available for the One for All via advanced codes. For more information, check the One for All forum and also check www.hifi-remote.com.

Mike
www.SurfRemoteControl.com