[Darkbyte]

A high powered magnet can be used to set relays , a relay is just a electromagnetic switch (A coil of wire that becomes a magnet when electricity passes through it). This has been used alot lately to bypass electronic fingerprint locks , keypad locks ect.

You would need to know your stuff , ideally having access to a the internals of alot of slots to find one where a relay would even make a difference and figure out the positioning needed for the magnet. Other than that I don't really have any ideas.