You can use one electronic flasher relay (same as we use for LED directionals) and one electromechanical relay.
We're only looking for wigwag. They'll be blue lights and not active (off) during non emergency.
Looking at the diagram. When the wigwag switch is turned on current flows to the electronic flasher and the common pole on the mechanical relay which power the right pod light.
The flasher powers the relay coil and it opens the normally closed contact to the right pod light and applies current to the left pod light where it goes through time cycle #1.
After time cycle #1 completes, current to the relay coil is stopped and the relay falls back to the normally closed position and powers the right pod light for the period of time cycle #2
This repeats over and over again as long as the wig wag switch is turned on.