How Can I Slide bones with Splin IK along Curve for tank tread?

Hi,
So ive been trying to animate some treads for something like a tank or snowmobile. Ive got a circular curve set up marking the path the treads would follow. Ive got all the treads rigged up to a series of bones and a Spline IK constraint applied to the last bone in the chain.

So all the bones are aligned along the curve correctly, however how do move/slide the bones along the curve?

I had something working a while ago using a curve modifier on the tank tread mesh(no bones). I got it so it could slide along the curve, but since modifiers don’t work in the game engine that didn’t do me much good. I was hoping Spline IK would give me similar functionality with bones so that i could just insert key frames for every step of the movement along the curve till i got a smooth loop that could be used in the game engine.

So, anyone have any ideas? i would really appreciate some help. Ive been scouring the internet for a couple days now and cant find anything that really helps me.