I do this often. The detaxe windows recently moved, but they are near the United economy check in line(somewhere around Porte 26). You need (1)the detaxe form which indicates the items bought and price and is issued to you by the store,(2) your passport, and (3)your ticket or e-ticket. A boarding pass is not necessary, since having the item available for inspection is also required,although I have never had to produce anything. I have, however, sometimes had to explain what the item(s) was, when the bill was sufficiently vague. After the forms are stamped, you put the pink one in the return envelope and take the green one home with you. I agree that the credit card refund is the most practical for the vendor to reimburse you for the VAT.

For what it's worth, the agents seem to inspect Vuitton more often than anything else.