Volume Guid and Powershell

Hi,

As we are using Hyper-V clustering and rapid SAN provisioning it makes sense to attach VHDs using volume GUIDs such as 

"\\?\Volume{3e199f9f-5c93-11e3-8130-d4ae5201ad09}\\Vm1Disk1.vhd"

I can attach the disk using powershell and WMI but not using the new "New-VHD" method.

In fact I am unable to use volume GUIDs at all in any file related functions as it doesn't like the "?" character I think which is technically an invalid character in a filename.

Is there any secret way of escaping a volume guid so that powershell can accept it.

Thanks

Daniel