Digging though my capx files I found a couple solutions.
Here I did wall sliding that works best when the wall angle is 45 degrees from the angle of motion.
viewtopic.php?f=147&t=91933&p=719471&hilit=event_motion2.capx#p719471
And here I used SAT in one and used the custom movement behavior in the other to compare. The first is spot on perfect but the moving object is treated as being perfectly round and it only works with rectangular walls.
viewtopic.php?f=147&t=95108&p=736233&hilit=slide3.capx#p736233
Hope that helps.
PS.
SAT stands for the Separating Axis Theorem and basically gives more info about a collision such as penetration depth and closest direction to resolve the collision.
EDIT:
Another idea that is more like steering is to use two detector sprites attached to the moving sprite. Then when they overlap a wall one turns clockwise until it's not overlapping and the other turns counter-clockwise. The just set the angle of motion to whichever detector that turned less.
https://dl.dropboxusercontent.com/u/542 ... steer.capx