How to install:
At the moment of release the beta doesn't support modding directly, so installation can be a bit tricky and you'll need to edit pak01_dir.vpk every time Valve/HPE releases a patch that updates that file. This'll probably change at launch/sometime after launch. 1) unarchive the materials & models folders into steamapps/common/Counter-Strike Global Offensive/csgo/ 2) BACK UP PAK01_DIR.VPK IN CASE YOU SCREW SOMETHING UP! 3) open up pak01_dir.vpk in Notepad++ or some other proper editor (Regular notepad will probably break your pak01_dir.vpk, so don't use that) 4) Use find & replace to find all instances of pist_p250 and replace those with anything else, say, pist_p251 for ease. What this does is basically it points the VPK to a file that doesn't exist, and forces it to load loose files - ie. new models/textures. 5) Go in game and enjoy!
How to uninstall:
Restore backed-up pak01_dir.vpk. You can delete models/weapons/*_pist_p250* and models/textures/weapons/Millenia/RedRogueXIII_Tokarev, if you so wish. Not necessary, tho.