Never done it, but I've researched it when I was contemplating doing so for some European calibers.
You decap by piercing the primer from the back and prying it out with a dedicated berdan decapping tool. Or hydraulically. Fill with water, insert snugly fitting rod, whack with hammer, pressure pops the primer out the back. Messy. No way to do it with a decap pin as there is no way to precisely locate the 2 flash holes.
Primers are NOT interchangeable. Boxers have the anvil as an integral part of the primer, berdan have the anvil on the brass.