The plugin page does list Xobox as being supported so you should follow elborak's advice.
It seems that several of the plugins are not supported on the Gigabeat ports for some reason. I consulted the plugins page in the Wiki and several blank entries are conspicuous (e.g. Midiplay, Search, Sort, Viewer, VBRfix, etc.). I'm not sure as to the reason for this. Does anyone have info on this?