Thanks for the mentioning lululee :) but I think the question points in the direction of how to actually get the ERC for the JCM.  In Poser 8 one can use the teaching tool to let it compute the deltaAddValue. I am not an expert and only played around a bit with it, but maybe it could help here?
My ERC knowledge is limited. I tried to understand it, but failed to do so.  Indeed I thought of rather inventing my own ERC system through python.
But back to the question: What do JCM's have to do with superconforming? I would think that a conformed cloth inherits the bend twist rot dials from the base figure. The JCM should inherit the bends of the cloth item itself, no? So: Figure  controls Cloth controls JCM?
But I am not an expert :)