DefianceIndustries has posted an extensive guide to help aspiring modders who are interesting in customizing Prophecy or Secret Ops. Wingnuts still have to be willing to stretch and be creative, but the document sets them on the right path by starting with an introduction to the various tools and how to work with different files. Then it moves into more complex subjects like hard points, collision spheres and texturing. Take a look for yourself here.
Here is the first tutorial for modding Vision with a vanilla install. I know it's kind of putting the cart before the horse a bit (since I still don't have a complete update pack) but I wanted to write it while it was still fresh in my head. Anyway I thought I could contribute to everyone's light after dinner reading.