You probably got a little more reading to do in the manual. I know there is no 890 manual but any of the other remotes that have variable and if/then/else commands will be the same for programming. Look at the 1200/5000/6000 manuals their variables are similar. You can do more complex things like track which input you are on if you don't have discrete commands for inputs or a work around.

The 890 does have push and hold, it is under IF. It works like this if press time is >= (how many seconds) THEN do this ELSE do that. Variables are the same way. IF you have this condition THEN do this ELSE do that. You'll see the options in the manual.