This thread from the 2008 election time frame and the included link may be helpful: http://www.cancuncare.com/forum/living-cancun-riviera-maya/10005-register-vote.html
I don't know if Zina will decide not to vote just to keep her distance from the home state she mentioned but it is one of the quirks of our federal system that elections of our Senators and Congressmen as well as our President are managed by the states- not the Federal Government
the consular agent in PdC will take your application and send to the US for you (and I think even process teh absentee ballot)?
There´s help online for those who want it. Everything that can be done is being done to make this a simple process, including assistance from the Consular Agents, locally, it seems from Kathy´s comments. But the effort still has to come from the voter. They can start here- Federal Voting Assistance Program - Home - To Vote Absentee, Start By Telling Us Who You Are
