This tutorial comes in the form of one PDF. It is six megabytes big, because there are many graphical explanations to the process. You can download it from the link below.
You will need the Adobe Reader to view the tutorial.
Silent1Unknown, the author, also included an example base for an AR file (the file used to put the car into MM2), some example textures and an example 3D model designed to work with the game. How it all works is explained further in the PDF file.