Of course. The simpler the better! 
This is all about the AlarmClock Time adjustment:
Sometimes I want to change it, so I created 2 Number items (Hours and Minutes).
When one of these change, I run this rule to get the actual AlarmClockTime and modify it with the new time.
In the background I use the AlarmClock from @rlkoshak
Alarm Clock Rule - Add-on Marketplace / Rule Templates - openHAB Community
Obviouly this did not work with the Rule to move it to the next day (but I am still investigating)
To Today - Add-on Marketplace / Rule Templates - openHAB Community