Dropping to planche works just like Yuri said. You also need to focus on staying hollow, without piking, which is quite challenging. Im not sure, however, how healthy this type of training is for planche if yuo do not have a very strong handstand(and preferably handstand presses). Im sure it is easy to put too much pressure on the elbows and shoulders too early, so be careful with this one. Make sure to turn your hands out as well if you do not have very flexible wrists.
Technically it is also different, as you need to focus heavily on only initiating it from the shoulders and never letting your legs drop, because if they do they will get momentum which will make things very difficult. This can of course be done in tuck, split, half lay and full.