For an outside installation, the soil around your foundation must be excavated so that the footing is exposed. For an inside installation, a section of your slab floor will need to be removed to expose the footing. The slab will be restored after the installation.
A section of the footing will be prepared for each foundation pier so that the pier is supporting the wall directly, and not simply lifting the section of the footing that extends beyond the walls. This makes for the strongest installation.