Jason, do you have Ron's book? I'd think that whatever percentage of CA is given for Mark Osterman's lantern slide formula would be a good place to start. I'd give it, but I don't have the book with me at the moment.
Is your emulsion in a hot water bath when you're adding the hardener? It seems quite incredible to me that it would harden up almost immediately unless it wasn't being heated to a proper degree. But then again, I'm just speculating.
Hardeners need time to work once coated; maybe even a day or two ideally. The lower percentages of chrome-alum will probably work, but give it enough time to work.
Could you give a more detailed outline of your exact procedure?
Best of luck!