In all cases just replace existing car.3do (back up original first). If your car folder does not contain a 3do file then just place the virtual mirror file in there and it will be used over the one in the DAT folder.
I'm not sure if the 65 files are compatible the the most recent car updates but it's easy to make your own.
Edit: The tutorial uses illustrations to show how to adjust the mirror position. See PDF version 2 posts down. The "How to make a virtual mirror" PDF is a PDF of text lifted from a RSC post by Alan Dickeson of how to actually create a mirror from scratch. As I say it isn't that difficult if you just work through it slowly.
Edited by ginetto, Jun 23 2015 - 01:48 AM.