Need a function (C++/OpenGL probably)

i have a lot of game programming experience but i need something i don't know how to do and we're coming up on a deadline pretty hard. i *think* it's easy (maybe trivially easy) for an experienced Torque/graphics person. i asked on the TGB forum but no one had a (concrete) answer so maybe offering cash will help

Input: a SimSet (or whatever) of t2dImageMap objects
Output: a single t2dImageMap

In the old days (because i am old), images were arrays and i could get direct access to the pixels, which makes it easy to merge two images. Nowadays, i'm told you use render to texture. i'm not a graphics programmer, i don't know how the Torque engine represents images and i'm a little short handed with programming right now so, as much as i'd love to, i just don't have time to dig though the engine and figure it out myself

From http://www.nvidia.com/developer, i'm led to believe you can do it with glReadPixels()->glTexImage*(), glCopyTexImage*() or glCopyTexSubImage*() and a direct render to texture method (but it's non-standard; i need something that works on OpenGL 1.1 ES or whatever is on the older iPhones) but i'm not sure how to integrate that with the TGB engine

i need this because, when i display 30 images on top of each other, the game can slow down. i'm hoping not using 30 sprites mounted to an object will fix that. There are hundreds of images, picked at run time, so i can't pre-combine every possible combination in photoshop

If this makes sense to you and you're thinking "what a maroon, that's super easy", let me know what it would cost to do this