Check out this site for free Hotkey scripting language AutoHotkey or AHK Index page • AutoHotkey Community
I recommend AutoHotkey_L variant as it has enhanced features. AutoHotkey_L
They are free and there is a forum to ask for help.
What you want to do would be extremely easy in AHK. See the script below:
run, notepad.exe ; change notepad to whatever program you want
When you run the program it sits in the task tray. As soon as you close it, the normal PrintScreen function returns.