It works in theory but is let down by cheap or poor execution. If you have had British cars, you will be aware of the general principles of how the cable moves the wiper arms via a rack and pinion type spindel at each wiper.
The system is just a crank wheel and connecting rod moving a spiral wound cable inside of a metal tube sheath. Up to you to bend the sheath and flare the ends to locate the ends of the tube. The sheath leads the cable around any convoluted path you want and is terminated at each end with a flare.
Where the designer went home is with the black lid that goes over the system. The lid needs to hold the connecting rod into the crank wheel and into the "piston" that moves the cable back and forth. The first problem is that if you tighten the lid, it traps the connecting rod between the lid and the crank wheel.
The other issue is that the lid needs to trap the flared end of the guide tube ( green scribble). The flare fits nicely into a slot and this would all work great if the tightened lid was not still more than 1/8" away from the tube flare. This is where it failed in that since the flare was not tight, it wiggled upwards out fo the slot and started moving back and forth with the inner tube. The solution was to weld in a 1/8" pice of flat steel on the underside of the cover so that it pressed the guide tube flair into place when the lid was tight, The 1/8" plate is also a good idea because the lid itself is a bit flimsy to to the job even if it did reach the flared tube.
So with the flair clamped down tight, and the lid level, the connecting rod being the highest part of the system is clamped solid against the crank wheel. The solution was to cut a keyhole in rouhly the shape of the diagram that I drew. This exposes the entire drive mechanism. However, since it lid is what holds the connecting rod in place, it needs a cover. Lucky for me the needed extra clearance was the thickness of the original cover, and all I had to do was weld a piece of tin over the new cover.
This all seems to be working well at the moment. The wipers are supposed to self park, but they do not. Not sure if that is due to the Miata control interface or the wiper system design. Don't care cause I have wipers that will do the job for now, if you can related.
The wiper vendor is aware of the clearance issues. The proposed solution is to use nyloc nuts under the 4 #10 corner screws to adjust the height of the lid. It needs to be angled higer at the crank wheel and tight at the tube guide end. It does not work very well.
If you do buy one of these systems, there are two prices to be bound on ebay. One is like $125 or so and one is much more, I bought the one suggested here but expect that they are the same.
I mention building my own next time and probably what I will do at some point. That would simplify the wiring, give me park and make replacement easier if the motor fails. Not being constrained by the extreme cheap design criteria, I could build a better drive system and still keep the cable drive.