Software Development Kit
The Renegade X Software Development Kit (SDK) is a publicly and freely available set of tools and resources to enable the creation of custom content, such as custom levels, mutators, game modes, and more.
Source
All of Renegade X's source code is available in the SDK, and is located in the "Development" directory in the SDK. All of Renegade X's game code is written in UnrealScript.
Assets
All of Renegade X's assets are available in the SDK, such as vehicles, levels, infantry classes, meshes, sounds, and more. Users of the SDK can create any level, and are not limited in what they can create.
Tutorial
kenz3001's YouTube tutorial series of videos for the SDK are available at [1]. More Renegade X related videos are also available on kenz3001's YouTube channel at [2]. Havoc89's YouTube tutorial series of videos for rigging vehicles in teh SDK are available at [3].