It's the same for any non-EU national spouse of a EU citizen (be they Spanish, British, German, etc.)
This information was current in November 2011.
The information sheet is:
http://extranjeros.mtin.es/es/InformacionInteres/InformacionProcedimientos/documentos2/103.pdf
The application form is:
http://extranjeros.mtin.es/es/Model...icitudes2/19-Tarjeta_familiar_comunitario.pdf
Briefly translating the required documents, you must bring:
1. The application and
a copy (always bring at least two copies of all this documentation to be safe!)
2. The original passport and a copy of your
entire passport.
3. A recent (issued within the last 3 months) copy of your marriage certificate
or certificate of being a civil partnership
and copy.
4. The original and a copy of the EU-citizen spouse's documentation (If Spanish, their DNI)
5. Three recent photographs "
tamaño carné"
* While it's not listed on the info sheet they asked us for an
empadronamiento indicating that we had been living together at least one year.
** If any of the documents (save the passport) are in a foreign language, they need to be legalized (Apostille of the Hague or, if the country is not a signer, other legalization) and translated into Spanish.
Check and see if you can get an appointment online at:
https://sede.mpt.gob.es/icpplus/citar
If not, you need to go to the office and wait in line. In Bilbao, this is at least a two day process. The first day you wait in line for them to give you an appointment (No, they don't tend to let you choose what day your appointment is). Then, you go back for your appointment and submit your documents. They'll inform you by phone or letter when you need to come back to complete the process, be it for an interview or simply taking your finger prints and paying the fee.
I have an American acquaintance in Madrid who just got married and wasn't able to get an appointment any earlier than November 2012. The wait time will all depend on where you are and how busy the offices are.
The non-EU national must apply for this documentation or at least an appointment within three months of arriving in Spain (or getting married).