Generally speaking, the manual does provide a good starting point. Just follow your settings on the rear track shock that coincides with your weight. Typically for powder riding you want the suspension a little softer than normal but not to the point of bottoming out all the time. After that start with the front track shock for adjusting the ski lift to your liking.
Just remember to adjust one thing at a time and I guess I like to take a few notes, so I know where I came from at least. I also like to mark the shocks, so it’s easier to keep track of your adjustments.
After that move to the front and play with your front spring pre-load. This really comes down to personal preference. Some guys like the front a little on the stiff side and the next will tell you to run then as soft as possible. Just try different settings and play with that until you find what you like and what works for you. Personally I play with the front shocks a lot depending on the snow conditions in order to get them dialed in for whatever you happen to be riding on.