Yeah, you could always use the OldX, OldY trick..
Should be something like this:
create three instance variables OldX, OldY and A
-sprite is overlapping
-- trigger once
set A to : angle(sprite.x,sprite.y,sprite.oldX,sprite.oldY)
-- system every tick
sprite move 5px at angle A
-else
sprite set oldx = sprite.x
sprite set oldy = sprite.y
-- (sub-event)