For any sort of lip-synching export you would need FBX. BVH is limited to body motions as you probably already know.
DAZ doesn't do well with FBX import, so unless there is a direct way to import FBX into VAM, I don't think it is possible.
I saw there was a plugin to go from from VAM to Blender to VAM, so that may be a starting point as you can import import from iClone/CC into Blender (there is a tool for that).