While it could be easier to just provide the modified iWAD, that would be considered pirating, so thats a big no (at least on official channels), all thanks goes to Zeikar for actually figuring all this out, i am just the guide writer.

Update: for a more direct approach that requires no file editing, use Diemas' wad: http://momodrive.darkhaven3.com/files/uncensored.wad

- Drop it in your doom64 install folder "...\steamapps\common\Doom 64"
- right click on Doom64 here on Steam, go to properties -> set launch options
- type "-file uncensored.wad"
- done :)

Be aware this method seemly disables achievements, the following method below does not disable achievements

How to make Doom64 a bit more like it was originally intended before the Red Cross threw a hissy fit in few easy steps:

STEP 1: Downloading

- Download this file: https://drive.google.com/file/d/1WMey12j9pob3Dvwp07UJ1XDOSrpCNnaA/view?usp=sharing
(This is the extracted image files of the original HealthPacks/BerserkerPacks, taken from Doom64EX wad).

-Extract file contents where you deem fit, just remember where you placed it.

- Download Slade 3, a doom wad editing tool: https://slade.mancubus.net/index.php?page=downloads

Install/Extract (depends on version you picked, either works)

STEP 2: IMG Importing

- Open SLADE
- Go to: edit>preferences>advanced, find iwad_lock and uncheck its box
- Open DOOM64.WAD, this should be in : ...\steamapps\common\Doom 64, where the "..." is your steam folder where you downloaded the game.
- Find and overwrite (import) MEDIA0, PSTRA0 and STIMA0 with the downloaded files, make sure your overwriting the already existing files, do not simply drag and drop/copy paste the files into the wad. In other words, find each of the 3 files, right click on them and click import.
- Save your WAD
- Exit Slade

STEP 3:

-Profit!