I would guess it's pretty similar to other native Junipers like CA, Sierra, Utah, Western and Rocky Mountain.
I might recommend the DVD How to collect Wild Trees which you can purchase at
www.goldenarrowbonsai.com. I thought it was very good and Andy collects hundreds of trees each year.
*Make sure you have a permit
*I like to use pure sifted pumice
*get as many fine feeder roots as possible
*In CA I collect either in Oct or early spring, however I don't know the best time in Texas
*I might suggest to start with a small or younger one the first year and see how that goes
*make sure you have all your aftercare set up before you go out to collect.
Good Luck!