Question: I was wondering if there is a way to use my GPU to speed up the training of a network in PyBrain.

Answer: 
Unless PyBrain is designed for that, you probably can't.

You might want to try running your trainer under PyPy if you aren't already -- it's significantly faster than CPython for some workloads. Perhaps this is one of those workloads. :)
Checkout Pylearn2: <https://github.com/lisa-lab/pylearn2>

It's a newer library and can run on GPU's with CUDA via cuda-convnet.