I have way back in the days but I don't think you're supposed to be able to. This is all going off memory being a kid...
In my situation the door eventually disappeared as I'd been on the level for days trying to open it. Likely something to do with the door failing to render because the game was riddled with bugs.
Inside there are 4 zombies with the same model as the other zombies in this area but are named Skriptors. There are 3 weapons in there and these are all duplicates of weapons you can already find in the game. The 3 weapons are: Whisper, Sword of Ashes and Deathwish. All of those weapons are found in the radiant citadel levels after the catacombs.
Looking back, I think this whole little spot was a hat tip to their devs and the work they put into the game. Skriptor being the Scripters who needed a nap.
TLDR - Yes you can if the game bugs out in your favor but it was never intended to be entered.
