This is the best I've come up with so far with about 20 minutes of work. 1. Create (or load) tree from tree lab 2. With tree selected do a distance mask render, save image. 3. Create lattice and go to terrain editor. Load image and invert. Play with smooth and sharpen, etc until you get something nice. 4. Position and size the lattice until the branches are just laying on the tree branches. 5. Apply snow material. Only works from certain angles so may not be good for animations.