Ok, the regulator is toast most likely. If shorted to ground, it would pass way too much current and toast points/wiring/resistors. So you are going to have to get another one.
The wiring instructions are pretty clear but you have to remember this regulator was designed to be mounted to a metal body so you need to run a ground wire from a mounting screw to the chassis/engine/battery.
If your ammeter shows high readings but the voltage across the battery is under 15.2v, then something else is drawing current and causing a high reading (sticking window switch, etc).