This servo really acts just like a normal servo. If I were to use one of the standard servo libraries, 1500us would be the stop speed, something like 750 is max reverse and 2250 for max forward. It can also be set for continuous using the programmer, but I'm currently not using that option.
Edit:
Sorry that is still confusing, yes 1500 would be the 90° position, 750 is max reverse position and 2250 max forward position.