I think you are misunderstanding the relationship between OpenCL, OpenGL, and mining.
OpenGL (and DirectX) is an API for drawing graphics on the screen using the GPU.
OpenCL is an API for doing calculations using the GPU.
Things like mining, F@H, video encoding, etc need OpenCL because they are all essentially trying to do a lot of calculations as fast as they can.
Hopefully you can now see that it is not relevant if your card support OpenGL. It really must support OpenCL.
Of course, OpenCL is just a standard API and before it came along, programs could still do calculations with the GPU, they just had to do it with the proprietary APIs from ATI and Nvidia. In theory, someone might make a miner that used the proprietary APIs to do the calculations on a card that didn't support OpenCL. But there hasn't been any real demand for that (because most cards that don't support OpenCL are so old that they would be crappy miners anyway).