Project finished.
- loosened the battery, shifted it to the left, to have easier access to the 3rd firewall rubber grommet.
- checked with a "hanger" wire, where the cables would enter the cabin (straight above the gas pedal).
- popped the rubber grommet out and pushed the cables through and put the grommet back into place (I stood in the frunk doing that, as it is the best place to access the grommet).
So the 4 sensor cables, two an each side, went:
1.) alongside the head lights (pulled them out and routed the cables alongside/below the head light mounting mechanism)
2.) through the 1st firewall inside the frunk (several cable ducts available right next to the head lights)
3.) alongside and fitted under the rubber sealing
4.) 2nd firewall
5.) behind the battery
6.) 3rd fire wall to cabin
