I'm making a program that raises/lowers sound volume, but I can't manage to make it detect when I hold down the Ctrl+Alt+Up Arrow Key

I need it to know when I press Cntrl+Alt+ArrowKeys even when the form is hidden or minimized as a system tray icon. Any ideas? I'm noy very good with API, but I guess that's where the solution's at.

Any help will be greatly appreciated!
(And please don't refer me to the keylogger example also in this forum, I'm looking for another possibility)