Learning from the Maxon 5hr rigging tutorial that came with r11.5 I picked up that joint IKs can be controlled via splines (Spline IK). The joints are drawn, then a B-Spline is set up to fit along, and handles at various points on the spline control the curvature of the spline. The joints then fit along it, either retaining the original length or stretching and squashing depending on the desired result.
Circle controllers set up so angles and positions are visible in viewport.
Full IK rig with controllers
A
