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If deltatime is holding you back then ignore it and do your motion without it and deltatime can be added later.
Anyway 8direction is simple enough to make with events. The main thing that's tricky is collision response or with those videos wall sliding. Here is a capx with the preliminaries of collision response.
dropbox.com/s/zf155w238lbomsw/event_motion.capx
It's incomplete as I ran out of time today. If you remove event 14 then it should basically work like the behavior. On a side note you can get motion with the behavior without acceleration or deceleration by setting them very high.
Anyway since you can't access the collision polygon from events you'll have to either make assumptions about the wall shape or devise a way to find approximately where the collision occurred and the angle of the side hit. One documented method floating around the internet is the separating axis theorem (or SAT). The only drawback is it's a bit lengthy and tedious to make with just events, although as a plugin it could be useful.
I'll try to finish the example up over the next few days.