If the open beam ceiling home is under construction, the piping can be put in the slab before it is poured. The vacuum tubing can be connected to the pipe coming out of the slab then run to the inlet. It is glued with the universal solvent that is designed to glue ABS and PVC together. The reason that you cannot use PVC pipe is because PVC pipe is designed for water under high pressure. It does not have sweep fittings.
ABS pipe does have sweep fittings.
On page 5 of Beam's manual it tells how to install an inlet in a closed wall. This is not as easy as it seems. Do not attempt this unless you have lots of time and experience with tools and construction. If you have to have the inlets in the walls, choose locations where the opposite wall is in a closet. Then you can remove a piece of sheetrock in the closet where it is not seen, and install the inlet in the opposite wall.