Hello Chis,
From MIDI pistons Hauptwerk allows you to load, save and assign combinations (and to load/assign organs, and temperaments) to/from any of their respective 64 'favourite slots' using their existing names (e.g. 'Combs01'-'Combs64'), and to view their short-names on MIDI-LCD panels. However, you can't specify your own (different) names for them without recourse to a computer keyboard (or touch-screen with some kind of virtual computer keyboard).
Also, you can save MIDI and audio recordings with automatically-generated filenames, and you can load the last-used MIDI recording, all from MIDI pistons. However, you can't specify your own names for audio/MIDI recordings unless you also use a computer keyboard (or touch-screen with some kind of virtual computer keyboard), and you can't browse/select MIDI recordings to load without using a computer keyboard or mouse or touch-screen.
In essence, if using solely MIDI pistons and MIDI LCD panels you can do any of the things that can be done solely within any of Hauptwerk's control panels, but not things that open prompts (e.g. file browse/save-as dialogue boxes).