I did it! For once, when approached by a Thai for directions, not only did I understand his request, I literally pointed him the right direction. After all the Thais mistakening me as one of them, I finally am able to actually contribute.
I can't say I used much Thai. I just pointed. Then tapped him on his shoulder and directed him. It was on the Skytrain. No knowing how to explain that he needed to also get off in one station and switch trains, I had to really direct him. It's just as well he was trying to go the same direction I did. At the exchange, I had him follow me and finally told him in my limited Thai "four stations."
Maybe it's because I had the American iPod earbuds on, or the fact that I was reading the Time magazine in my commute, or the fact that I was carrying a Whole Foods shopping bag (thanks, harraton!), or even the fact that I was completely unable to talk back beyond pointing and nodding, he finally recognized he had asked a farang for directions and asked in excellent English "Where are you from?" and acknowledged my help with a very gracious "Thank you very much."