How to create a global date entry shortcut/hotkey?
Well I'll be damned... I had a solution the whole time.  I use BetterTouchTool for various gestures on my trackpad, but had forgotten that it could trigger text sequences as well, including current date/time.  Mapped them to shortcuts and voila, works great even in a Java app!  Admittedly it uses a 3rd party app but it's one I was already using (and woefully underutilizing its features, clearly!)