I am not sure about Mach and Lazy Cam but every CNC I have used has some form of cutter compensation, activated by G41 to the left of the programmed path, G42 to the right of the programmed path, and G40 to turn it off.
Your CAM program should have some way of adding these codes to the G code program it produces.
There are usually many options somthing like.
Computer: The offset is done in the CAM (the G code is the centerline of the end mill but offset from the part by the size of the end mill you tell the cam you are going to use) and does not use the above G codes.
Wear: The offset is done in the CAM like above but the G41,42 are put into the program and if the endmill you use is not exatly the size to told the cam you were going to use you put the difference into the machine controls tool offset table.
Edge: The cam programs the edge of the part and puts the G41,42 comands in the G code and you put the full size of the end mill into the machine controls tool offset table.