I've used MiMiC quite a bit recently on a project I'm currently working on. Now I'm not a total expert on the subject so I'm basically speculating here but it would seem to me that theoretically, because MiMiC generates a .pz2 file for the character, that this would be the file you would want to try and edit as opposed to the .cr2 file. If you open it in Notepad, I think what you can see is the keyframe number and the relative dial position for the particular body part, so if you can isolate the exact keyframe and body part in which you want to affect a change and either decrease (or in your case increase) the parameter setting within the file itself, this might work. I wish I had time to experiment with it and give you first-hand knowledge but it might just work and could be worth a shot.