well its fairly easy to get there, but i have to check with my dad to see the best route to get from the reynosa-mcallen road to downtown. But i think its fair to say that you keep going until you get to Cuauthemoc ave. ( its fairly big and lots of pointers along the road, cant miss it, but it takes about 10 to 15 minutes with no traffic to get all the way there. ) When you are in cuauthemoc ave. immediatly take your left, and turn left on the first ave, that allows it. About a block away is the Pino Suarez ave. that runs upwards ( Cuauthemoc ave. runs downwards ) and then you turn to your right on constitution ave. ( the one that ends up at the Monterrey-Reynosa road ) to the right, but DONT leave the far right line. Go down until you run into some statue ( you cant really miss it. ) and on that ave. turn to your right. Keep going until you find the Hidalgo ave. and on Hidalgo turn right and you will eventually run into a long line of metal looking dudes =)
Its fairly complicated now that i see it, but i guess if your friend from monterrey remembers a bit he'll figure it out.