Interesting thought - how about using metaborate as an alkaline stop for Pyrocat-HD?

The Sodium Carbonate equivalent of Pyrocat-HD 1:1:100 can be mixed by adding 10ml "A" to 1 liter water with 6.3g Sodium Carbonate (monohydrate). I would use significantly lower concentration in a presoak bath, probably just enough to tip the pH to the alkaline side.