Take off the top hose and pour 50/50 directly into it.
Yes, park on an incline and run it for awhile, topping off as it drinks it from the resevoir bottle.
Keep a couple gallons of 50/50 with you at all times just in case you didn't get it all, and keep an eye on the temp gauge. Pull off immediately if it flips to red, CAREFULLY remove the res cap (after you let it cool a bit..and do it with a rag) and fill it up. Turn the car back on, and watch the res to see if it drinks more down...then fill it up until it stops drinking it down.
Some get really stubborn for some reason. It took me about a week to get mine to stop overheating due to air locks...but I never tried the nose up trick.