I've been using hyper-v to create my base images for deployment to workstations. I create them on a Dell PowerEdge 2900 server running Windows Server enterprise 2008.
The Dell OEM key does not activate the guest O/S.
The server was originally purchased without an operating system. The O/S was purchased separately and is in a Microsoft VLSC account, so it does not have a COA with a virtual key (which dell indicates would be one solution)
Are there any other options?
To address the title of your question, you don't.
To address the content of your question, get a non-OEM key that doesn't violate the EULA.
If you bought your licenses via some sort of Microsoft Volume Licensing agreement, then your keys should be available within the VLSC portal. Presumably, you got the ISO for Windows from there - just go to the Product Keys area and use those to activate your system.
The documentation you describe is for using the license and media that would have come with the system if you bought Windows with the server - so it isn't really applicable to the situation.
Edit: It seems like there's some serious confusion about how licensing works. I'd recommend you find someone who can help you with the basics. I'll also add that licensing is hard, so there's only so far we can help you here. But at bottom, you have to license at least two instances of Windows - the Hyper-V host, and each guest. Consider them to be separate devices - each must have a proper license, and its appropriate key.
(And I see someone mentioned Win7 earlier. You're not trying to activate Win7 with a Server license, are you? That won't work at all.)
Use the key for Windows 2008 server found in the VLSC portal. Hyper-v is the thing inside the host emulating a computer that is running you guest OS. To activate the guest OS do as you would with a regular system and use the windows 2008 key.
