Synchronising Ardour and MuseScore
I've had to work this out again since reinstalling my laptop so thought I might record the result here...
Typical issues found when trying to get Ardour and MuseScore to work together is that MuseScore jumps around in a BAD way when it hits tempo changes from JACK, or it locks up, spewing lovely digital detritus into your monitors.
The best method I've found thus far (although it still does that lockup thing from time to time) is: