You are allowed to use CUDA or OpenCL with FireMonkey.
I mean, FireMonkey is not disabling OpenCL/CUDA when it uses DirectX/OpenGL for rendering.
This is the meaning of the FAQ.
Pure truth. No lie.
(I admit I went to a jesuit university) :)
So you need an OpenCL/CUDA library and compiler. I suspect you can use this open source project, or this one, or write an external CUDA dll with another compiler, more integrated to the CUDA/OpenCL programming. Some sample code here.