There's this script, which essentially puts the information from the manual on-screen for you but otherwise works similarly to the built-in UI:
A more simple (but also more limited) UI where you don't have to type anything and just click buttons to adjust things could be made with a similar script. Or you could make some toolbar/menu buttons which do things like add/subtract 1 hour from different timestamps and use that as the UI.
Depends on what you want exactly.