Setting vdreport for IPv6

[mpounsett]

I'm using VirtualBox on FreeBSD, from ports (virtualbox-ose-4.2.20). I'm using 'VBoxManage modifyvm --vdreport' to set the virtual display port, but this appears to only modify the port for IPv4. I can't find anything in the docs that modifies the IPv6 port.

Having set "--vrdeport 3300", when I start the VM with VBoxHeadless it reports:
07/01/2014 07:11:29 Listening for VNC connections on TCP port 3300
07/01/2014 07:11:29 Listening for VNC connections on TCP6 port 5900

And netstat -an concurs:
tcp6 0 0 *.5900 *.* LISTEN
tcp4 0 0 *.3300 *.* LISTEN

The docs don't seem to mention an alternate v6 command line option for the vrdeport. Is this missing from the docs, or am I just failing to spot it? Or is it missing from VirtualBox entirely?

The docs for --vdreaddress[1] are similarly unclear when it comes to running dual-stack. It looks like you can specify a single v4 address or a single v6 address or listen-on-all for dual stack, but not a specific v4 and specific v6 address.

Does anyone know what the proper syntax is for these v6 options? Or does VirtualBox just not have feature parity between v4 and v6?

[1] I was going to put the URI to the vboxmanage-modifyvm-vdre docs here, but apparently I'm not allowed ot post URIs. See chapter 8.