When setting up a car in LFS you can set the caster somewhere between 1 and 6 degrees for the GTR cars, and very accurate (up to 2 digits behind the comma). I was wondering if (and how) this is made possible on real cars? Is it really possible to have such a range, and is it also possible to set it up with such an accuracy?

dunno how its done in real cars but on rc cars its usually done by tilting the whole suspension (something that lfs cant simulate yet afaik)

As with most of the adjustments on the LFS setups road cars will usually be limited to either one or a few options in big increments.

In racing cars most adjustments are made by feel, because no racing car will ever be exactly the same they can't just be setup with the same settings as they had before a rebuild, some of the current top level cars will be an exception to this as they are so precisely constructed that the same settings can probably be recorded and re used.

Cars are dynamic things, every component in a racing car has a life and will wear, it's the penalty of making them so compact and light, nothing is excluded from this, the big Capri bodyshells used to buckle and twist and would finish a race a different shape to how they started it. If you replace something on one side of a racing car you have to replace the other side to ensure they will wear equally and therefore the car can remain balanced.

Quote from Shotglass :

dunno how its done in real cars but on rc cars its usually done by tilting the whole suspension (something that lfs cant simulate yet afaik)

Does that have the effect (or side-effect) of inducing anti-dive and anti-squat in the suspension, that may make the car behave quite differently?

afaik anti dive and/or anti squad are set by tilting the rear axle on rc cars
(maybe i should have been more specific in my pervious post in that you tilt the front axle to change caster on a rc car ... but then again im sure you figured that out yourself trist)

the only use of side effects for tilted front axles in rc cars except caster that i can think of atm is that off roaders usually have it to handle bumps better (like the rc10 b4 on this picture: http://masters.cz/catalog/images/as9050x.jpg )

With a MacPherson strut it's something like this on the attached picture. That's the upper mounting point of the suspension from under the hood. You simply can move around the whole thing and fix where you'd like it. Although this pic is pretty old, there are some newer one's. I've seen one, and in that the camber adjusting screws are moved elsewhere, but the caster adjusting is the same.
I haven't seen a double wishbone kinda one, but I think with that it's just changing the position of one of the A-arms with spacers or something.
Anyways that .xx accuracy is more like just for troubleshooting or at least I only heard people doing that with it. There are very expensive suspension analizer machines that can mesure everything about it with a laser beam and that can be so much accurate but it's just for compare the two sides if they are asymmetric(in a bad way ) or not, because a lot of things can get twisted when you hit another car or even a higher kerb.