Schindler 330a Hall Buttons to keyed

Anyone have a simple way to install on/off key switches on these? Is it even possible or do we have to order entire hall station/boards from Adams? I don't see any type of keyed hall station available on the website. Ideas?

Pm me your email. I'll send you some info

The bottom of the hall callboard should have a black plug in jack. This is for the key switch. However if your looking to add this you will need the male connector for said jack. But yes its possible and yes its simple.