Fred -
A feature of BESR is the ability to convert an image file to ESX, but that probably doesn't help in your situation.
BESR needs to access the backup location through Windows. Thus, if Windows cannot see and have full access to a location, neither can BESR. Correct me if I am wrong, but the ESX server doesn't allow anything else to access the data share other than VMWare. I don't think it's even possible to setup an SMB share or similar Windows access points.
On the other hand, what you are trying to accomplish is fully supported. You can create an image of the VM to another location while the VM is running. Once done, wipe out that partition and create a new, larger partition. Then restore the image file back into that partition using the Restore Anywhere option using the Symantec Recovery Disk. Virtual or Physical - BESR will do either. It is not necessary to convert the BESR image file (.v2i) to a VMDK first, although converting to VMDK is another BESR feature.
Does that help?
Andreas H.
Symantec BESR Team