Proper leakdown test procedure

[Honus]

A search of the threads on leakdown tests reveals a split between those who do leakdown tests with the piston at TDC and those who do it at BDC.

For those who do the test at TDC, how do you ensure that the motor doesn't spin? I am particularly worried about spinning the motor backwards if I don't get the piston precisely at TDC.

For those who do the test at BDC, how do you ensure that both valves are fully closed during the test?

By the way, the factory service manual says to do it at TDC and to make sure the engine doesn't spin. Unfortunately, it does not say how to keep the engine from spinning.