I would like to understand how to connect the Hella Bistable Latching Relay https://www.delcity.net/store/Latching-Relays/p_818110.h_818111 The intended use is on a motorcycle to turn on and off an accessory by tapping a button which momentarily connects to ground. Each tap would sequentially turn on or turn off the accessory.
judging from the diagram That relay uses terminal 6 for positive and you ground terminal 1 or 2 to turn it on or off.
so to get it to do what you want would require an alternate acting push-button.
it's probably easier to use a latching push-button with an ordinary relay.
Or use a bunch of ordinary relays to build an alternate acting bistable
You can't do what you want with a single push-to-make button.
A bi-stable latching relay would be a simple solution but I don't think they're available in automotive versions.
Figure 1. Go to HomoFaciens and click "Start animation" to see how the pawl mechanism is advanced on every impulse of the relay coil.
No flip-flops, electronics or magic is required. Wire your button between the power-supply and the coil. Each impulse will change the state of the contact.
Imgur doesn't seem to like animated gifs.
To use your relay some electronics would be required and you probably want it to reset to the default position on power-up. All things considered I suspect that a latching push-button and a regular relay would be a simpler solution but it won't have the power-on reset.