Sure. No prob. First, re: chameleon vs. ultragreen, I like chameleon for its stiffness and abrasion resistence (also, if it gets abraided, it is easy to see because it gets a white crusty look on the brown exterior). I wouldn't suggest mixing the two line types because the difference in stiffness can cause knot breaks. I have never found the color of the chameleon to be problem. I use tip pieces in 8lb virtually all summer, even with small (size 8) hairwings tied low water style. If I feel the fish are particularly spooky, I go to 6lb, but I think it is more for me than for the fish. As far as the formula goes, it varies a bit depending on the length of the rod, the weight of the line, and the size of intended flies.
In general 42- 48" of your stiffest butt section (40lb for heavier speyrods, or large flies, and 30lb for lighter speyrods and smaller flies, 25lb for smaller single handers), followed by 28-30" of your second butt section (30lb for heavy, 25 for lighter, 20 for single hander) ,and then 6-10" sections of each consecutive line class down (25, 20, 15,12, 10, etc.) then the last section (whatever lb test you choose to end with, should be 24-36". The reason I gave ranges for the lengths is to allow for flexibility so that the total length is equal to or greater than the rod length...calculate the leader length you are shooting for, the number of sections you will be using, and then adjust the lengths of the sections withing the specified ranges to achieve the desired total length. It is important NOT to skip ANY line classes as this will reduce the efficient transfer of energy. Also, I use only blood knots because they enhance the stiffness as well, and create a smooth, streamlined look.