Assuming you have downloaded the files (typically as a .rar or .iso ), here is the standard process for :

This is the "holy grail" for builders. This tool allows you to apply any pattern or color to almost any object, clothing item, or surface in the game. It provides a level of creative freedom that hasn't been replicated in the series since. 3. All-in-One Installation

It provides a "frozen in time" version of the game that includes the final official patch (1.67 or 1.69), ensuring maximum compatibility with modern community-made performance fixes like the Smooth Patch or NRaas mods.