enable unused commands

[Joe S]

I have SH4 running well with just a few mods and I would like to keep it that way. However, I would like to enable a few commands that are currently unavailable. Is there a way to check to see if a certain key combination is not used before I use it for a new command? Otherwise, I will screw one thing up in order to use another with the result that neither will work. Thanks! Joe S