I think I might try to hook up Marsyas and Flash with XMLSocket, and then to the Make Controller via OSC.
I could also hookup Marsyas to neko, and then neko to Flash, but for the high bandwidth data that I'm going to need, I think hooking Marsyas and Flash directly together might be better.
I'll have to research this some more.
Make Controller Kit
Make Controller Ruby interface
Make Controller Flash interface
OSC resources
OSC in C++
OSCPack - a set of C++ classes for packing and unpacking OSC packets.
OSC CNMAT downloads
Guide to OSC Libraries