Is the Attorney Pro Tem provision in art. 2.07 the only authority for appointing a stand-in prosecutor?

... on what you mean by a special prosecutor or stand-in prosecutor.

This issue is discussed in great detail in the annotations to Art. 2.07 found in any of TDCAA's Criminal Laws of Texas books (see pp.171-173 of the new 2007-2009 version), but without more detail, it's difficult to give a concise answer to the question posted.

For example, it makes a big difference if the elected DA is recusing him/herself, or is he/she just temporarily appointing someone as an assistant? In the first case, the pro tem is acting as the DA, because the elected DA is out of the case. In the latter, the elected DA still retains control over the case just as with any other assistant DA, and the "special prosecutor" is not a DA pro tem.

See Heath Stephens v. State, Austin Ct. of Appeals (about 1998)
See Darnell Hartsfield v. State, Texarkana (2006)

Sorry, I'm on the road and don't have the cites handy.

Bottom line, there are 3 ways a DA can bring in someone to prosecute a case in his stead:

1. As a DA Pro Tem under 2.07. In that case he recuses himself and the DA Pro Tem takes full control over the case. An order recusing, as well as an oath of office is required.

2. He can deputize someone as an Asst. DA. The local DA is not recused and the appointed assistant acts as any assistant would. A deputation and an oath of office by the appointed asst. DA is required.

3. He can appoint any attorney as a special prosecutor. The DA maintains control and management of the case and the special prosecutor need not be deputized or even take an oath of office.