Hello,

If you want to go the way of the notary, the Spanish word is NOTARIO, as John Downs said.

Being Spanish, I don't know how things actually works in Mexico. But found these two sites offering directories of Notaries. Just choose the state and the city:

Directorio de Notarios en Mexico (on the right side, "Encuentre su Notario" = find your notary)

http://www.notariadomexicano.org.mx/directorio/index.html

I don't really know means "notarising the document" (in Common Law), but in Spanish Law, being a private contract, you can "elevar a público el contrato", which means a notary gives public faith of it, usually done for real state private contracts to register them. Being a private contract, it becomes a "public" contract. If he refuses that, another option would to ask for a "(foto)copia compulsada" which means that the notary guarantees that the photocopy is made from the original. That way you would have notary stamps and signature on the photocopy and you could keep the original aside.

Last, to make the notarised document look (and BE) very official, ask the Notary in what office of the Public Adminstration in that city you can get the Apostille of the Hague Convention Stamp ("Apostilla de la Convención de la Haya") on your document. This way it will have inmediate effects (and MUST be accepted) in all countries part of the convention. Check the list -not only the map- and you'll find some countries you will be crossing.

Have a great ride!

Esteban