1. You can't
2. You can draw very large circle (radius 300 nmi or more) where small "section" will be "almost line"
second option is to use many smaller triggers (with destination circle) next to each other.
3. Every trigger can start or end in specified time (page 3)
In this case large number of destination triggers creates "virtual line"
Best to add 1 more aggregate trigger for binding all above.