I think what I want to do is not possible, but maybe someone has a clue.

I have a Samsung TV that has multiple HDMI Inputs. I want to program macros into an MX-450 to "Watch TV" or Watch DVD" activiites that require selecting the right input. The remote that came with the TV has a "Source" button that will step through the varius inputs, but since the existing selected input is an unknown, it needs to be directly selectable for a macro to work. There are no HDMI1, HDMI2, etc. buttons on the remote that can be learned. However, discrete codes do exist for each input. Is there a way to capture these codes and use them in an MX-450 macro?

I thought about programming those codes into a Pronto and then having the MX-450 learn them using the Pronto as the source. I think that should work, but it is cumbersome.