Simply take a proven recipe of whatever constitution you like and substitute a PW insert for 1/8 ounce of shot. This is the standard practice endorsed by the maunfacturer.
If you have a favorite 1 ounce load of a particular velocity and pressure, load the exact same components, except drop 7/8 ounce of shot. The PW insert takes up approximately the same amount of space as 1/8 ounce of shot....meaning the crimps should be similar...but weighs considerably less....meaning, if anything, a slight reduction in pressure and a slight increase in velocity. Of course, to concoct a 1 ounce spreader, you start with a 1 1/8 ounce recipe.
Velocity and choke will influence your results and there are further refinements to the process, should you become interested enough in making the best spreaders.
