Defendant has a single 20 count indictment. 10 counts of distributing child pornography and 10 counts of possession. Each count relates to a separate image so theoretically the jury will be able to return 20 guilty verdicts.

What if anything do I need to do for the judge to have the option of ordering potential prison sentences to be run consecutively?

File a motion to cumulate sentence citing Tex. Penal Code Ann. § 3.03(b)(3)(A) as authority for ordering possession of child pornography sentences to run consecutively. There's a sample motion in the back of the TDCAA Investigation and Prosecution of Child Sexual Abuse manual on page 260, with notice of intent and order on the next few pages. It's probably not strictly necessary to do so; there's authority that Tex. Code Crim. Proc. Ann. art. 42.08(a) vests a trial court with discretion to cumulate a sentence without the necessity for a motion by the State (see e.g. Strahan v. State, 306 S.W.3d 342 (Tex. App.—Fort Worth 2010, pet. ref'd). The better practice would be to file a motion, though.

If you need a sample motion to stack, I have one. Email me.