Instructions
Tap the tilde (~) key to open the developer's console.
Type "player.additem 000000F X," replacing "X" with the amount of caps you want. The amount of caps you need depends on how many caps you already have and your barter level. Without any caps or barter skill, you must add 5,000 caps to your inventory. However, the price of all items changes inversely with your barter skill. For example, the pristine Nuka-Cola machine costs 500 at no barter skill but will cost 450 with a barter of 100.
Press "Enter" to add the caps to your inventory and to close the console.
Travel to the vendor who sells your upgrades. If you live in the Megaton home, Moira sells your upgrades. If you live in Tenpenny Tower, Lydia Montenegro sells upgrades. However, if you let the ghouls occupy Tenpenny Tower, Michael Masters will sell your upgrades instead.