Keyboard shortcuts

[Eddie]

I feel like I should either know this, figure it out on my own, or find
it on Google, but I can't.

I would like to assign a few keystrokes to launch programs, for
example, Ctrl-F4 to open the terminal emulator. There is a Settings |
Keyboard | Application Shortcuts, but Add does not allow me to input a
keystroke. It's the same on every Xfce distro I've tried.

Can I do this? I don't mind editing a text file, if it is just the
interface that is busted.

Thanks,

Eddie