How do I get breading to stick to pre-cooked chicken for pan frying?
The three step method should work for this.  

This being dredge the cooked chicken in flour, then egg wash and finally the bread crumbs(ideally Panko bread crumbs).

The other way is to do a tempura batter.  But to make sure the tempura batter is effective, make sure to dredge the chicken in flour first.

Good Luck,

I will be doing this soon and I can give the results.  The three step method is the best method I have found for breading and frying meats in general.