bc,
Not needing anything specific, just tried to get Katrin's option a shot.
What I did was:
->Create VP
->Edit annotation crop
->Insert a VW break Line (on a angle)
->Drew a polygon following the breakline
->Delete breakline
->Exit viewport crop
What I would like is for the breakline to be an actual visible line and the rest of the crop invisible, using Katrin's method.
BTW, no negative reflection on Matt's tool - it's great.