Candescence directed me to this:http://www.sonicfangameshq.com/view.php?sec=6&id=1
a 360 degree trace movement engine made in the games factory, it included the *.gam file so I was able to look at how it was done.
Although it used 22 events, I had a go at remaking it in Construct and managed to do it in 6
The principle is simple. Two 'detectors' come out the left and right of your character and shoot off downwards. The angle of your character is then determined by the angle of one 'detector' to the other. Finally, you move your character up or down so they are standing on top of the ground. However 'down' and 'up' are in relation to the angle the player is at.
Quite a simple and eligant system really.
With these new method in mind, I'll make some additions to the 'custom movement' so such functionality can be available in a much easier way.