In the street near the workshop, up the road a bit towards the big tree in the middle of town you will find a sewer manhole leading to the home.
(Right out the front of the destructible house closest to the workshop)
The home is modelled from the Railroad HQ area. I have cleared out pretty much everything except the lights as it gets pitch black otherwise.
I also completely re-worked the navmesh, so your followers can run around wherever they like and wont get stuck where things used to be in the original Railroad HQ.
(THIS DOES NOT AFFECT THE ACTUAL RAILROAD HQ, IT IS A COPY OF IT)
I have added "Secret" doors leading to P.A.M's area and the escape tunnel, just because it suits the whole "secret base" theme the railroad had going, but they never really utilised the secret doors as much as they could have. (Primarily because Npc's can't open them)
It contains a workshop and powered switch-box (700 power) and a sizable building area, but is NOT a settlement (You can't send settlers/supply lines here. but it DOES work with the immersive teleportation mod if you really want to get resources connected)
But now for the MAIN feature (Honestly, it was just me learning how to program the terminals, but the result was AWESOME so I kept it)
*** UPDATE***
Like an idiot I never included the scripts for the terminal, they are now included.
As such the area mentioned below should now function as intended
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The old firing range area, with the wooden "triggerman" targets... I felt that was a bit lame.. it's too small and the ground is uneven so it's not much use as a building area (you CAN still build there if you want) So I re-designed it as a weapons-testing area.
It now has a jail cell accessible only via a nearby button, the ramp has been removed so the "Subjects" can't escape and it has a nearby terminal and spawner button that allows you to choose what type and amount of enemies to spawn inside the cell for you to either watch a massive brawl, or test your favourite guns on (All Npc's spawn with no guns, otherwise they would shoot you. Although Assaultrons DO still have the head-laser... you've been warned)
On top of that, it has a security shutter and "Sterilization Protocol" to kill any npc's inside the cell should things get out of hand.. (You can spawn up to 100 of each enemy with each activation of the spawner, so things can get pretty hectic.)
Otherwise it's just an empty player home for you to build in, with secret doors because why not?
Also, If you have Scrap Everything installed, put it AFTER my mod in the mod load order, or you will lose Scrap everything's functionality in sanctuary. It's just how the game loads the mods, it has to be very specific with what scripts load when etc