A "beaching kit" involves either shortening or replacing the overload valve spring in the T&T pump.
Basically, all T&T units have a valve that will bypass hydraulic fluid and allow the motor to tilt if you happen to hit something solid like a log, container or the beach. It's a safety measure to avoid your motor or transom being damaged. Generally the spring that holds the valve (often a metal ball) in place is set to hold the valve in place quite strongly so that reversing the boat with a bit of throttle won't allow the motor to lift. Shortening the spring (or even fitting a lighter spring) will allow the valve to overload more easily.
Lots of outboard technicians try to make it sound like a major conversion kit when in fact it's often just a reasonably crude "grinding down" of the spring. I was quoted R1500 to have it done by an "expert". Instead I got hold of a parts list for my motor, figured out where the valve was and fitted a lighter spring. It worked a treat.
Each manufacturer's T&T unit differs. If you're a DIY ninja then tackle it yourself, otherwise find a tame techo that won't smoke you to do it.