First, using a particular tool is not cheating, it is just a choice of technique by the individual craftsman. There are several ways to ensure a perpendicular hole. You could use a well tuned and set beam boring machine if you have one around. You can use a square (or squares) as a reference to check the alignment of a brace-and-bit or an auger. One of the more popular methods right now is to create a v block and to use that to keep the brace at right angles to the bench face.