This has nothing to do with Hotkey, but maybe it could be of help to you..
Do you know that you can tell BSplayer to change resolution when you activate FullScreen?
Go in General settings (ctrl+p -> General) and select
"For full screen mode switch to" 1024x768 (there's also an option to change resolution at startup "At start switch to").
I hope this features can help you..at least until developpers don't accept your request..
