Thanks for the email. Unfortunately, we cannot implement support for Forest Colour as it was designed to work on the CPU. In fact, the only GPU renderer currently to work with Forest Colour is V-Ray GPU, and support had to implemented by Chaos Group themselves.
That said, FStorm appears to have some features that will allow you to get something similar. In this case, I would convert the existing Materials using FStorm's built-in converter (which seems to do a pretty good job) and swap out the Forest Colour maps for FStormMultiTex maps set to Object + Element ID
We're currently evaluating whether to add materials for FStorm. There are a lot of renderers out there and we would love to support them all, but resources are limited. If there is enough demand though we will, of course, convert our materials. As you are probably aware, the situation for FStorm isn't helped by the legal wrangles with Otoy.
All the best,