Yes of course, if you do want to get certified there are several ways to do it, and I like to do it slightly differently from the way Elbert evidently does.
If you have say two weeks with a few evenings free before you come down it's a viable option - you need to find a local PADI dive shop and buy the Open Water Manual and read it. Email the shop here that you intend to use and they should give you additional guidance. Or log onto the PADI.com website and register with them for on-line learning, though that's a more costly option.
Elbert runs the White Sands dive shop about three miles north of town, and if you're staying anywhere in that area you won't go wrong by using him - he's one of the most experienced instructors around. Write back here for his email address (though I'm sure he's reading this thread).
Otherwise we at Protech would be happy to help you.