Hmm well I might not know how to do this, and I havnt tested it either. but wouldn't the basis be that , make a region at the ramp ,
Unit enters region
Unit equal to Demon hunter (or whatever your unit is)
Remove
Another trigger:
Unit enters region equal to Demon hunter (or..)
Create a (make a new custom unit starting from a demon hunter, type of path: Flying or levitating, and heigh (how ever high you want him to jump) Call this unit example: Demon hunter 2) pointing - which ever degrese your dm2 is pointing at then when the dm2 enters region (landing spot) remove dm2 and same thing creating your dm again..
Hopefully this should work. Or not since i havnt tested it, but the trigger is something in that style.