I would not describe it as a technique.
You gotta have a strong forward with your thumbs in the A’s.
You gotta really know that your wing is overhead before unhooking your thumb, to then, try and fumble around looking for the throttle button.
Then, when you find it, you will mash it down and go to full throttle.
With the instant thrust, and your wing still overhead, it will either throw you in the air, or overwhelm your ability to manage that much thrust.
You will then back off the throttle and go to zero thrust.
There is no nice and easy linear feel to the throttle. (It is there, but will take a bit of practice!)
You will provide plenty of amusement to your pilots buddies until you get used to having that much push… In a spring loaded throttle, when you go from Zero to Wide Open in 3/8 of an inch!!!
This is the original push button thumb activated throttle.
I think they may have provided a more sensible set-up on the Post 3 V-4s