We are currently not aware of any DVD burner that can also burn a CDG format disc, using Track At Once, which is required to do a custom assembled disc. I doubt seriously if Sony will have a DVD drive that does CDG read/write. Historically, Sony did not do a good job of supporting the CD+G spec in their CDR/CDRW drives.
We are expecting a drive within several months to be available, but they have already changed their specs once. Thus, we are not sure if they will offer CD+G capable reading and writing.