1.Place The Roast Inside A Slow Cooker Coated With Cooking Spray. In A Separate Bowl, Stir Together The Beans, 2 Cans Of The Chile Peppers, Chili Powder, Cumin, Salt, Oregano, And Garlic Powder. Pour The Whole Mixture Over The Roast, And Add Enough Water So That The Roast Is Mostly Covered. Jiggle The Roast A Little To Get Some Of The Liquid Underneath. 2.Cover, And Cook On Low For 8 To 9 Hours. Check After About 5 Hours To Make Sure The Beans Have Not Absorbed All Of The Liquid. Add More Water If Necessary 1 Cup At A Time. Use Just Enough To Keep The Beans From Drying Out. 3.When The Roast Is Fork-Tender, Remove It From The Slow Cooker, And Place On A Cutting Board. Remove Any Bone And Fat, Then Shred With Forks. Return To The Slow Cooker, And Stir In The Remaining Can Of Green Chilies. Heat Through, And Serve With Flour Tortillas And Your Favorite Toppings.