Can't believe what I'm reading here. The motor can only turn in one direction. And no matter what that direction is, you can still control the correct movement of the wiper blades. So LH/RH argument doesn't hold water and swapping neg and pos would be stupid. This situation will only arise if you have stripped the assembly or if one or more of the pivots had stripped and the operating arms are no longer correctly configured.
You have to run the wiper motor normally and turn it off at the console so that the motor is in the starting position. Note the direction of rotation of the motor and mark it on the casing for reference. Then you have to configure the operating arms so that the next revolution of the motor will cause the arms to move in the right direction.
It takes a bit of thinking but it's as simple as that. And believe me - this is the only correct solution.