Mow the ivy growing past its bounds with a lawn mower. Wait two weeks for the vines to begin resprouting. Spray the new growth with a glyphosate herbicide. Follow the package directions for application instructions.
Pull up the dead ivy vines growing into your neighbor's yard. Pull them up from the tip, slowly moving along the length of the vine so you can pull up the dead roots as well. Continue pulling until you reach the spot where you want the ivy to grow. Cut the vine off at that point with gardening shears.
Pour 1 qt. of water into a bucket. Add 5 tsp. of borax. Mix with a wooden spoon until the borax dissolves.
Pour the borax along the edge of the vine growth. The amount of solution will treat an area of 25 square feet.