I have problems with ModDB (as always haha) So I can't download it.But I will try to explain it as easy as possible.
1. Get the Geck,if you don't have already get it here
2 Install and run it.
3 Unchek everything EXCEPT for FalloutNV.esm and the esp wich the mod adds (I assume its called Book of Earache.esp),select it as active file (by clicking on it and selecting "Active file" )
4 Wait untill it loads up,this could take some time so don't close it,it is not crashing.
5 Go to the "Cell view" window
6 select there in the "world space" tab "interiors" then for example if you want them to place in Mitchells house search "GSDocmitchellHouse" and double click it.
7 Wait untill it loads up,again it does not crash.After it is loaded you will see the interior of Doc's house in the Render window.
8 Switch to the Object window and go to "world objects" then click on "container"
9 Type in the "filter" bar "locker" and right click (for example) "footlocker01Empty" and click on edit.
10 Change its ID to (again only for example you can change it to what you want) 0001WeaponLocker.
11 Do not close the "container" window!!
12 Go back to object window click on "weapon". I assume that all the guns have similar base ID so they will be all in one line or at least close together.
13 Drag all the guns into the "item list"menu in the container bar I told you not to close.
14 After you dragged all the guns into the "item list" you click on ok and if it asks to creat a new Form say yes.
15 Now you have the container itself with the guns and only need to put it itno the game,to do this switch to Doc's house you opened before.Now just drag "0001WeaponLocker" from the Object window into Docs house and press "f" so it will be on the floor.Now you can move it around to your most liked position.
16.Now click on the little Floppy disk icon you see in the top left corner to save.
Now you just have to run Nv and visit Doc Mitchell and pick up the guns.
Hope this isn't that hard to understand