I installed two spigots yesterday on a Propex repipe. The second one went through the same hole as the original spigot. The hole was way bogged out, and I needed something to fill the space around the spigot, to exclude bugs, and hold the spigot in place. The epoxy snake took care of all that.
On the first spigot, the penetration had to be moved down the outside wall on account of the fact that the original feed pipe went up through the bottom plate, then up in the wall for a foot or so, then out through the sheathing and lap siding to the outside. I couldn't duplicate the route of the original pipe, so I drilled through the band down lower and abandoned the original pipe. I preassembled the spigot and propex adapter and pipe, and pushed it through the hole from the outside to connect to the main near the PRV in the basement ceiling. The useful piece of information in all this is the fact that the spigot with its adapter and compression ring fit perfectly in a 1" hole drilled in the siding. That left plenty of room for the two screws for the sill cock to get a good hold in the siding.