Top of the Line Material

This is an expensive program, but if you really want to see and master all the science of how the mouth moves, there is probably nothing better:

http://www.primalpictures.com/speech_language_pathology.aspx

On the other hand, you could start with this for FREE, and it is pretty awesome too, especially for the comparison's between English and Spanish:

http://www.uiowa.edu/~acadtech/phonetics/

Thoth

Reducing a Native Spanish Speaker's Accent in American English

My first thought is that, in addition striving for a scientific mastery of language sounds, you should probably try to find some formal program or course to work through.  Adult learners learn most things through independent study.  Your consultant will help connect you to resources, but finding a way to advance through your own independent routine and work is the key to mastery.  Something computer or video driven would probably be good to help pull you along and infuse more of a feeling of personal relevance into your work.  Here is one option, and it even has some free videos:

http://www.speakingyourbest.com/freevideolessons.html

http://www.speakingyourbest.com/americanenglishtips/spanishaccentreduction.html

Good programs these days usually have a lot of free material to get you started available on YouTube because they are confident that people will use enough of their material and find it helpful that that will then buy more advanced levels later.  Use that principal to find things to try out and then ONLY BUY what is usual personally to you.  (For example, other people who want to learn Arabic should use http://www.arabicpod101.com/ after they have the basics down.)

ALSO, in your scientific study of the language, you will need to master much of the international phonetic alphabet.  If you are really going to become a true master of the accent in a new language as an adult, you have to master the science of language: linguistics.  I will post more on that later.

Thoth