While the two steps above are important, it does not answer how to get green mc button to work.
I am not an expert (only a trial user), but this is how I got the "green button" to activate MC18. There may be better ways, but this seems to work for me. It is actually fairly easy, but as most things in MC18, too difficult to figure out.
To make this work I created a batch file that would "SetFocus" to MC18. The command in the batch file is:
mc18 /Mode Theater
Then go into Options > Remote > Commands.
Create a new command ie SetMCFocus
Add a Run statement to run the batch file.
After the command is created, you then learn the "Green Button" to execute the command.
Learning the command was most difficult part, I had to try multiple times to get MC18 to start learning.
I use similar methods to create a computer shutdown command. When I press power, I want MC18 to close and computer to shutdown - not go into sleep which I think is default. There is a ton of power with the batch commands. I also have a separate batch file that automatically loads TMT5 for my 3DBD ISO files and starts 3D playback.
If I can now figure out how to add Ctrl-J as a command my remote would be setup.