I've done this mod. You don't need the kit. There is a cover on the passenger side under the dash. Its held there by 3 screws. Take that off. Now keep in mind that this is a job for a circus contortionist. The directions for making the cut are good. Do that with some swearing and a sharp exact o or box cutter. The filter can carefully slide up there without all the brackets and stays put. You can even leave the cover off that you removed to get to this spot. The fit is really tight and the filter stays up there just fine.
I'll have to check if I have any pics of doing this. The filter does help keep the dust down inside the truck.