In order to use a traditional boring bar one must first drill a hole, using a center cutting end mill to plunge a hole then using it as a boring bar eliminates the drill tool change. Boring in a mill and boring in a lathe are the same with the exception that the part rotates in the lathe and the tool rotates in the mill. It also does not matter if CNC or manual as the operation is the same, all that a controller does is move the tool for you, it is not magic, the only reason that you can not easily mill a radius on a corner using the hand wheels is that your hands are not capable making the small variable moves required.
A drill/mill tool is essentially a boring bar that will plunge cut a smaller hole first then act as a boring bar when moved off center. The problem with using a standard solid end mill is that they are not as rigid as a boring bar thus the shallow hole, shallow being 3 X Diameter or so.
You may put an end mill in a boring head set on center and plunge then move it until reaching the finished hole diameter, the flutes must be oriented correctly however.
