A typical Near-net-shape hybrid process mills back a previously printed part. Another possible build strategy is to print directly on (sometimes previously milled) stock.
The primary consideration when printing on stock is to correctly probe and map the print area. You want to make sure that the origin point for the Z axis is set to surface that will be printed on. The X and Y origins will be more dependent on the geometric shape that will be printed.
It is helpful to reduce the speed of the first layer, either in the Simplify3D process settings or in the Diabase Wizard to ensure that the plastic has enough time to properly adhere to the surface of the part.
It is important to make sure that the auto-bed level sequence has been disabled by selecting the option in the Diabase Wizard.