CORRECTION! I went through this is May. The consulate no long issues this piece of paper. Was a bit upset because they use to charge $55 and it ended up costing me a lot more. Part of that was because we were running late, the elections and having someone else do something that we could have.
We were at the consulate at 7 in the morning and they told us they no longer handle this. So we then went to the civil office to get the license and the sign said that I needed one. Mistake 1) there was a notary and lawyer right next door to the office. The lawyer had the notary type up the letter (3 times because of mistakes) and then I singed, he signed, the notary signed. Then he claimed that it needed to be legalized. To this day, I cannot figure out why this needed to be done since this piece of paper was only used locally and was turned over to the civil office. I know on my wife's birth certificate and our marriage certificate they do not usually "legalize" it at the JCE but if you are going to use them in the US or for immigration then it needs those have to be legalized. (Side note: if you are going to use the papers in court there are like 3 extra steps to accomplish prior to be admitted in court in the US)
I would suggest that you start at the place where you are going to pick up your marriage license, and ask them. Also bring your passport you will need it for the license and for the letter as it is refernced in the letter, like they would a cedula for a Dominican.
Jerry