Instructions
Type "/j6" into the game's text window to travel to J6's House. As long as you are not in combat, you will be transported to the house.
Equip Skull Crusher armor onto your character. You can purchase this armor set from most vendors near the end of the game; multiple types of monsters drop it as well.
Walk through the force field. With the Skull Crusher Armor equipped, your character will be able pass through the force field freely.