The mysterious "plugin" package does not yet exist, and won't be in the 1.5 release. I would encourage you to try to implement it and send in the changes. The ideas in the execution modes doc are being steadily filled in by people who need them.
Do you have any pointers as to where do I start? I mean I can see how I can probably do it with a C bridge, but I don't know the runtime well enough to attempt to do it without it. Glad it's written in Go now :)
