Kiwi Cap Dry used to be an excellent pre-treatment when it was still available in a jar (non-aerosol). it worked almost too well.
The various current water proofing sprays for boots and outdoor equipment work to some degree but not as well as the older Camp Dry IMO.
I think I'll pass on pre-treating with Gink. I don't even like it as a conventional fly floatant. I prefer Fly Agra, Loon Fly Dip, High N Dry Liquid, and Silicon gel in that order. I suppose you could pre-treat with the first three options, but they work well enough when applied streamside to a fresh, dry fly that I don't see the need. Even when I pre-treated with camp dry I would apply floatant to flies just before use.