I piggy-backed an electric actuator onto the door lock rod on the driver's door. The keyless entry module activates the electric actuator which unlocks the driver's door and activates the switch which then actuates the pump which then unlocks all the vacuum actuators in the other doors. Relays turn on/off the factory alarm; spliced into the ATA harness behind the passenger footwell false firewall. Works great.
The Golden Rule
1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)