Re: Deadbolt lock
Make that 3 votes for using Houston's method. It will be the easiest. One major precaution will be to make sure that your setback is correct, don't just enlarge the hole where it's at. The set back is the distance from the edge of the door to the center line of the hole.
What I would recommend is a scrap of 1x6 or plywood. Draw a line across the face in the center of the board and down the front edge (from face to back ). Mark your setback on this reference line and drill your hole. What you should have when you are finished is a template plate that will guide your hole saw through the door.
Clamp the template to the door with the front edge of the template flush with the edge of the door. The line you drew across the leading edge of the template will be aligned with the center line of the bolt (hole in edge of door that holds the bolt that engages the jamb to hold the door closed ).
As long as your reference lines on the template are square to the leading edge of the template, then you will be drilling the hole in the right location.
These instructions are assuming that you're using a hole saw and not a Forstner bit. A hole saw will allow you to use the template in this manner, a Forstner bit won't.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!