How exactly does buying directly from Westvleteren work? Even if I managed to reserve some beer, it appears here that I need my own car, or at least one whose plate # I will know long in advance to pick up beer.  Has anyone done this?  What is the exact procedure?
I live in Amsterdam, and I have not personally been to Westvleteren but I have friends who have made the trip. It turns out that you have a few options:


You can call and make an appointment and IF you get an
appointment then you must drive there at the appointed time to pick
up your crate of bier. If you can't make it at the appointed time
then you lose out, and you must start the process all over again. I
forget how much bier this is for, but I think it is 24-48 bottles. Indeed when you make the appointment then you must supply your license place number which they use to keep track of you. They will not allow you to make 2 appointments with the same license plate number in a 60 day period. Additionally, the phone number you must call to get an appointment is always busy, I have heard of people using automatic redial for hours before they finally get through. 
If you are in the area (again you will need a car, because there is no public transport, and biking there is unreasonable from most places.) You can pop in and there is a small shop next to the monastery where you can buy a 6 pack per person without appointment, and also with out a huge price markup. Of course while you are there you can also eat some good food, and buy other items that the monks make and sell. This is much less hassle, but you cannot get much bier, so it may not be worth trekking all the way out there specifically for this.  However if you are in the area already and you have the time to take a small detour then you should certainly pop in for lunch or dinner and get some tasty brew.
Finally if you are in the Benelux region you can sometimes find Westvleteren in local shops or cafes, however the prices range from 10-16 euros per bottle (in Amsterdam) which is a lot more than you will pay at the monastery. (However, beer bought at the monastery isn't meant for selling, it's meant for private consumption, it says so every time you buy some)