I'm not from Texas, but I'm pretty sure soft-touch (ST) is universal.
When the masseuse stops with the regular massage and starts softly running her fingers up and down your body, that's the signal for you to turn over so she can service you.
If you've got an erection at that point she'll probably start right in. If not, then she might be looking for a signal from you. Just direct her with your eyes to look at your dick and raise your eyebrows.
If that fails, and you're sure the place is supposed to be erotic, grab her hand and put it on your dick, or just ask "Can you massage there?"