This is what I found for a 93 NA:
Bee*R - Miata
Green - Yellow/Blue (2G)
Yellow - White (2E)
Red - Red/White (1B)
Black - Black (2A)
http://www.bee-r.com/main/rev/revlimitter.pdf (Use M-14 to find splicing locations.)
On the Bee*R diagram, it only shows 3 of 4 wiring locations. For the 3 it shows, it goes Green, Yellow, and Red. (from left to right on diagram M-14.) The one wire that is not shown, is the ground wire. Either of the 2 black wires off the ECU will work for ground.
Not sure how well this helps.