Rig Animation Question

[RErender]

I am working a bit out my realm and trying to animate a seal swimming under water. I have him pretty well rigged up and am setting about to get him swimming, my thought is that it would be nice to get the rig to just follow a path for the major movement and then tweak the secondary motions by key. I have tried putting the spine bones on a path using a list controler so it will blend but can't seem to get it right...

Any ideas?