Remember How Important Safety Is?
If you are looking for a less-exotic locale, your local climbing gym may be the place. Most times, the bottom of the ladder here means belaying for birthday parties on weekends. Sometimes this will mean not getting paid in money, but in free climbing (which isn't that bad of a deal).
The best way to land this gig is if you have been climbing at that gym for a while. If the managers or desk staff recognize you (and not because of the number of incident forms that they have filled out with your name in them), they will be more likely to take you on as a belayer. They more than likely have seen you climbing there and if they know that you are safe (there's that word again), they will be more willing to let you belay for them.
In either case, this will get your foot in the door. After that, look for every opportunity to learn more and take on additional responsibility. And remember: ask them to train you to be an instructor. Fortune favors the bold, and managers aren't mind readers. Let them know what you want to do.
You Won't Get Rich
Give up that idea right away. Climbing is not a sport to grow rich in. You can definitely make a little extra cash, and most places have "pro-deal" arrangement with climbing equipment manufacturers that get you significant discounts on the equipment you are going to buy anyway.
If you are willing to take on some additional responsibilities, you may start to see additional opportunities to earn additional money. After acting as the senior instructor for a time at one gym, the head coach approached me and asked me to take on coaching their difficult "Kids Climb" group on Fridays. This gave me some additional hours each week. One of the more difficult kids, Zach, turned out to be a very talented climber when he got focused on it. We eventually arranged to take him out of the class and I started giving him private lessons, which paid $18 per hour. He went on to start climbing stronger than many of the older kids in the next program level up.
Overall, if you have a dedication to safety and a willingness to learn about the sport, you will see that there are opportunities to work as a "professional" rock climber. If you are really willing to sacrifice and live as a true "dirt bag" climber, traveling with the weather, living out of tents, truck flatbeds, and friends' floors, subsisting on ramen noodles and Clif Bars, you can go the extra mile and learn how to be a climbing guide. If that is something that interests you, contact your local guiding service or check out the American Mountain Guide Association web site.