If you think I'm going to lay out a procedure for you (considering I'm guessing about what would work) and have you follow it, only to find your clubheads sitting in a puddle at the bottom of a vat, you are sadly mistaken.
I think WBL (who is a metallurgist) confirmed that a couple of hours in a bleach bath would take off the outer layer of chromium. Then you could soak them in salt water, let them dry, repeat a few times until rusted.
Keep in mind that once they've started rusting, they will probably continue to rust forever.
But again - I'm guessing here, and won't be held accountable for the results - good or bad...
