Leon showed me how to do it at BTS show, With the head removed. You regulate the O/2 at 4 liters and put it into the top (with a hose in the middle of a cap) of the center hose connection and cap off the bottom, where you would have the connection to the canister, below the sensors. In 2 minute or less its done. He is working on more Caps and plugs to Kit it up for everyone to do it.
And off the tube for the oneway valve you put a hose to an O/2 Anayzer and can double check your readings.
He's (Leon) Very slick!
Paul