Haven't tried that but I don't see that it should/would make a difference.

The OEM remote works, but it only has a toggle on/off and I need the discrete on/off commands for a URC MX900 remote.

Again:

The URC database doesn't have this AVR listed, and the codes that are in the database will not work.

I checked on the Onkyo support forums and got a reply stating that Onlyo doesn't have the TX-NR414 in their IR database. I asked for, but have not received, the IR codes for the TX-NR515 which MAY work.

Perhaps there's an equivalent Integra unit and those codes would work?