As a secondary animation (no more than, say, a dozen bones or half that), relative to the flow of the main animation. I'm using Spring Magic (3ds Max script) for now, but it doesn't always look natural and requires a lot of manual edits. I'm wondering if there's a better way to do it. Also, without the need for MassFX or…
it would probably be a spring controller on a target for splineIK which is probably what Spring Magic does for you automatically (though I've not used it) :/