Measure out and mark the line for the holes that the pegs go in. The line of holes needs to be at least 3 inches from the edge of the work bench and down the length.
Drill 1- to 1 1/2-inch diameter holes at each mark, using a drill and a wood bit.
Cut pegs from scrap wood to fit the holes. Make your cuts a little wider than the hole and then sand or shave them down with a hand planer or sandpaper. Sand only 2 inches on one end of the pegs to fit the hole, leaving the rest thick enough so that they do not slip through the hole.
Install a vise on the end of the work bench so that it lines up with the row of holes. Drill screws through the screw holes in the vise and into the end of the work bench.