Here's the link to the owner's manual, but don't expect anything but generalized information in it. You won't find any step by step "model specific" information on any of the Keystone products.
http://www.keystonerv.com/customer-s.../owners-manual
You may also want to go to the Keystone video website and watch the video on winterization here:
http://www.keystonerv.com/customer-service
Three gallons of antifreeze should be enough to winterize your RV if you drain the HWH, blow out the lines and don't forget to blow out the P traps. Just pouring antifreeze down the drain will dilute the antifreeze with the water that is already in the trap, so emptying them first will save a little antifreeze. Don't forget to flush the toilet until pink appears !!!!
You'll need 3 or 4 ft of tubing and a flojet adapter fitting. You can get the fitting from any RV dealership and the tubing from any hardware store or big box store.
Don't forget a #2 square drive screwdriver (or bit and drill driver) as you will definitely be taking some things apart to access the pump and bypass valves.
Here's a picture of the flojet adapter fitting. Simply pull the blue tab on your water pump, disconnect the input hose, insert the adapter with your hose installed, push the blue fitting closed, insert the hose into a gallon of antifreeze and turn the pump on, continue opening and closing faucets as pink appears.