I'm a current 3rd semester student at UTMB. I didn't find out about UTMB until halfway through the admission cycle (which was longer 2 yrs ago), so I only had the 20 hours of "official" OT when I applied and they were all at one site - don't know if that's changed now. However, I had worked for a number of years and had multiple of volunteer work that went along with OT. My GPA is pretty high, but most of it is from 5+ years ago.
My suggestions to those applying are to apply as early as possible! There were something like 250+ applicants for 54 spots last year. One good thing about UTMB is they don't hinge interviews on GPA alone (albeit they require a 3.0 min), so that means chances to let yourself shine - but also that you're competing against way more people.
However, one girl in our class now had been waitlisted and had actually started the OT program at UT-El Paso I think. She was contacted about a week or so before orientation began last August - she packed up and came on down! So there's always hope. 🙂
Good luck!!!