soaking

Hi all, new divers who just invested in x2 Apeks XL4+ kits for me and my wife. After reading the manual it specifically says about pressurised soaking the regs for around an hour, which I intend to do. TLDR What kit should I get to pressure soak the regs. I was intending to get a "spare air"...

So the other night after a salt water dive I was rinsing all my gear in fresh water...as we all do. I put the dust cap on my first stage and submerged the whole delivery/info system to soak for about 20 minutes. (Atomic T3 first and second stage, Aqualung ABS octo, Atomic Cobalt 2 computer) yes...