I use an electric hot plate that I purchased at a garage sale.
I also use a large 2 gallon pan.
Place the pan of water on the hot plate and heat until the water boils.
Place the crooked stick with the crook over the pan and cover with an old coat or blanket, but be careful not catch the coat on fire.
Let the stick stay in place for about an hour or so.
Remove the stick and bend over your knee until straight, a bit at a time.