Start installing the marble track by first installing the first lifting device and then add track and elements until you have worked your way around the room.
Keep looking ahead to make sure the track you are installing is not lower then the next lifting device. You don't want to spend a bunch of time designing a lifting device and then have your marble track end up lower than what the lifting device can accept.
One thing that helps in the placement of the track supports is to mark all of the studs in the wall (if you plan on attaching to them) with blue painters tape. This will help you figure out where you want the track and element supports.