I did some research on the subject.
All that i could find was this:
I was quite disappointed when I realized that there is no communitiy remake of this mission for PC. There are quite some user made missions available for download, but not this official one. I tried doing it myself, but with no success. Cinematics weren't a problem. PS2 edition uses PSS format, and Xbox edition uses BIK format. Both of them can be easily converted to whatever format PC requires. As for maps, this waren't the case. In PC edition, maps are packed into PK3 format, which is actually renamed ZIP archive. As for PS2, it uses RDF format, and Xbox uses CACHEMAP format. I did quite extensive googling and, unfortunately, wasn't able to find a way to unpack those. I came to conclusion that only way to play that mission is to play it on the actual console, either PS2 or Xbox.
... quote from user Eqagunn from this wikia talk page http://wolfenstein.wikia.com/wiki/Talk:Return_to_Castle_Wolfenstein
It seems that you only have 2 options, one realistically:
- you can emulate the ps2 version with the pcsx2 emulator. The game should run fine on a modern system with a better resolution even.
- extract the PS2 files. The game engine should use similar map files and model/texture data to the formats used by the PC game engine, but as stated by Eqagunn on wikia, the extraction process can be hard or non existent most probably because of proprietary archiving formats. Let's not forget that the console could be limited compared to the PC data files, data corruption, engine restrictions etc.
- there is a slim chance that somebody already managed to do this and release a mod of it. Haven't found anything in my searches. Maybe some daring modding team is developing a copy of the prologue missions on moddb, so give that site a try, I may have missed them, but highly unlikely.
In conclusion, the only practical solution is to emulate the PS2 version. The XBOX version could be trickier. There is an emulator in it's infancy because of even bigger softwarehardware restrictions, so slim chances of extracting those data files altogether.
Maybe a petition for a director's cut to the game's devs could be made.
Hopefully this answers your question partially about making this available for PC.