I guess keyboard shorcuts are allowed to only have a single character + modifier keys. That means you could define a shortcut like Ctrl+Shift+Alt+F, but not sure, didn't test that in Creo Parametric 4.0 yet. Kinda limited, but it's done the same way in other CAD apps, such as SolidEdge and SpaceClaim 2016 as far as I know.
For multiple-character shortcuts for functionality, see mapkeys. These can invoke a single command as with keyboard shortcuts, or go further and do multiple commands, or do UI within the commands, etc.
