First: This is not the magic spell to solve the question, but, as the question is very broad, my answer hopefully describes a reasonable strategy to tackle the issues at hand.
I see one problem: While LaTex is used to create a visual representation of a text, TEI is exactly the opposite. It just describes and encodes things that can be identified in a text, mostly independent from a representation. Because of that, the only reasonable way from LaTex to TEI is to create a representation of the LaTex output in a XML-close format (e.g. HTML) and then to convert that output in TEI. So you need a two-step procedure.
I think that one of the tools listed here will help you to generate a nice HTML output, probably LaTeXML comes very close to what you need. After that, you will need to translate this HTML output into TEI. If HTML elements are sufficient for you, a more or less simple transformation could already do the job, but this depends on requirements you did not specify.
There is, by the way, another question here that touches your question, maybe it is of interest.