Found this video: https://www.youtube.com/watch?v=qmDrwDscv5s
And found out that DAR files which contains KMD files which are Models, and PCX files which are Textures are in stage.MGZ and MGZ files are just renamed ZIP files and you can just rename it to ZIPs and Extract it.
There's also a DAR extractor called MGSRipper apparently made by someone named "Ameneko"
So I searched the name up and found this http://forum.xentax.com/viewtopic.php?f=10&t=5485
Apparently MGS2 PC also uses DAR files but they work differently.