The Lee is NOT the best tool for the job as you cannot adjust the crimp stations.
You did not say what Alliant powder you bought
Go to the Alliant website and go to the reloading section and find what components you need. Components are NOT as interchangeable as in metallic reloading. FOLLOW THE PUBLISHED RECIPES
You would be better going to a trap/skeet club and seeing if someone is selling a MEC Jr. on their bulletin board - or check Craigs List and cancel the Lee LAII