I do my JCM by first making a morph (the hard part), then just copying the JCM channel from the figure to the clothing, or rather just leave it in if you use the figure's CR2 for your clothing. Once you have the channel, all you have to do is copy and paste 3 things into it from the actual morph you made - the deltas, indexs and numbdelta lines. Takes a couple of seconds in the CR2 Editor. Like I said though, making the morphs right is the hard part, though.