All you will need to perform this masturbation technique is the ability to squat down and lean back on something. The benefit for your effort may be an amazing sensation during orgasm in your legs and lower body if you can get the lower muscles stretched out nicely.
(1) Squat down in front of a bed or other low object and lean back making sure to flex the leg muscles all the way up to the anus.
(2) Place one hand on bed for support and leverage if necessary.
(3) Masturbate in with any variety of hand techniques
(4) Try tensing up the muscles right before and during ejaculation.
(5) Go easy and don't hurt yourself. This is not a natural position for the body for extended periods of time.
Be sure you are not straining any thigh muscles to maintain the position, because you will not be able to stop, once the first orgasmaic tingle occurs.