Is it possible to override the default incoming call screen with a custom screen on the pebble watch?
Im guessing I could capture the interruption as described here - http://developer.getpebble.com/guides/pebble-apps/app-events/app-interruptions
Is this sort of customisation possible?
The screen that shows an incoming call is a modal window shown by the system and cannot be overridden from a Pebble app running on Pebble.
There are however two things you can do on the phone: