According to my email inbox, this area from the technical side still has not revealed it's secrets to all the racers, so here's a quick short story on how I do it. No garantuees of course
The glue is use is called 'Plastic Welding Systems' Ill check it's overall brand name when I'm at the club again. It's immensly strong, only downside is, you only have about two minutes from the point you are mixing to when have to leave it alone. So make sure you practised a few times before you use glue.
Use equal thick blocks on four points around the car, doesn't really matter where as long as it somewhere near the wheels. These block determine your ride height. Advised is to use doublesided tape to tape them to the techblock, but don't forget that this tape has a thickness to! Don't forget that when determining the height. Then, no matter what kind of bodyholders you use, take the time to set the widt of them up correctly to the sides of the body. They should touch, but that's it! The body should slide over them, without any (and I do mean ZERO) force. It should 'fall' right on the blocks. A 0,1mm free play is sometimes even easier to work with between the holders and the body. Take your time to set this up!
Now, wether or not you're using the same glue is me, or something else, you would want a nicely formed profile by the glue, and also 'press' the glue in the corners. to achieve this I take some easy flexible tape (Tamiya masking tape) and put it on the holders, and fold the half of the tapewidht backwords, leaving round 3mm blank on the holders, that's where the glue should go.
Clean the body and holders properly! Now put the glue nicely divided on the holders, and don't hesitate to use a little more then you would think. Cause when hardened, you can always dremel some out again. Make a narrow, but thick 'pile' of glue on the holders, and don't let te glue stick out to much to the sides. Then take the body, and put one side first over the wheels, with the body to far out, so it won't touch the glue yet. Carefully slide the body towards the holders, and in one motion stretch the other side of the body over the other holder on the other side. Don't use actual force here, but just the normal stretching from the plastic itself. Gently 'wobble' the body around a very tiny little, as this will make you feel if there are no parts are loaded. make sure of course the positioning is correct, and if you do a good job, you'll feel, during the wobbeling, that the body will slide back on the blocks. Then you know it should be ok
Last but not least. Before you start the whole operation, find something like I use; plastic coffeespoons oftenly have a round end on one side. That round end is perfect to gentle push the tape, and the glue under it, down into a nice profile, and will fill up any uncovered areas. This should be done directly after the positioning of the body is done. Especially on the Ferrari's, you have an enormous open windscreen, through which you have easy acces to the holders, to push the tape down with your coffeespoon. Wait till your glue is fully hardened out, and you should be ready to go. After the hardening the tape should be fairly easy to remove.
Hope this helps!