I believe there were two types, the type you have seems to have picked up the name 'Can Am' system. You can get additional information about how it works from here:
http://www.doveperformanceparts.com/Accessories.htm
It uses a sprocket on the crank and a special timing cover.
The other system is known as the GT-40 system and it uses the internal pump, but the external pump is belt-driven and mounted off to the side.
I'd call Dove for details.