If you own the megaton home. You need to Kill the butler (He will come back ") ), get everything out of the house, and start up the mod. When you get in you will see the butlers body. Open the Command Prompt (With "~" ) click on the body (the butlers name will be at the top in quotes) and type "resurrect" to bring him back to life. Finely to get the key to the basement, you need to go to the project purity basement. If it is locked because you already activated the purifier, then open the command prompt and type in "coc ppurityos". It will Spawn you in the right area. Now just find the key card in on of the rooms.
Also get the patch: http://www.nexusmods.com/fallout3/mods/12339/?
FIX CRASHING (3 comments)
Also get the patch: http://www.nexusmods.com/fallout3/mods/12339/?