making an automotive "dizzy" switch with using a latching relay
Relays have different "forms" with standard pin numbers.  While your Hella P/N does not seem to match up with their catalog.



The upper relay uses Set + Reset inputs using dual SPST contacts to Gnd with 12V to pin 6.    

The lower relay uses bipolar DPDT contacts to reverse the current in a coil at both ends then open with  3rd SPST contact or the DPDT switch has a centre off position.

My guess is you have the 1st one.
Latching relays require much more current. (e.g. 120mA to drive 20A)

Alternative.   


Normally one only needs a momentary SPST relay to drive the solenoid.
electric oil pump in ACC position  
All coils need a snubber reverse diode to clamp the arc current on release to V+, rated for the same current.
do you really want the starter motor to keep turning on its own (latched) in a theft scenario? ( not a great idea)



  On my old '63 MGB the solenoid had a manual pushbutton as part of the solenoid to do what the mechanic wants. But that was under the hood.