When I did mine, and yes they are HPM megabite(awesome arms by the way), I used a bottle jack to push the control arm up(compresses the spring) and I used a come together (same as a chain jack just with a cable) to pull the axle foreward to the control arm, since it fell backwards. By adjusting both the jack and the come together, I was able to line the holes right up with no drama.
I hope you are doing one side at a time....
Ted