I doubt this is possible the way you imagine it. There is no reason for them to implement it in complicated way. Considering that this is IR remote that does not get re-programmed like BT one, it will be unwise to hard-code there channel id (like say "12" for Netflix, "28" for Pandora).
Taking heed from the RokuLT manual at FCC
https://fjallfoss.fcc.gov/eas/GetApplic ... id=1548864, the 3 buttons are probably designated as QuickLaunch1, QuickLaunch2 and QuickLaunch3 - and the mapping which-does-what is done on the Roku (even if no user preferences exist for that)
You can of course try capturing the IR codes and see what the structure is.
Can Crestron do remoting over tcp/ip? Because Roku has network remoting protocol