KMS and MAK Activation using a single image file?

I've been testing WinVista Enterprise over the past few months and
been reading up on the license schemes. It seems to me that for a
medium-large corporate environment, a combination of KMS activation
(for machines that regularly connect to corporate LAN) and MAK
activation (for field site machines/laptops that could be off the
network for a while) would be the most logical approach.

With that being said, is there a way, post-image (I've seen mention of
a vb script), to force the machine to use one or the other? We have an
enterprise agreement with MS so our Vista Enterprise DVD does not
prompt for a key code during installation. I wasn't sure if the
activation is something that needs to be set prior to image capture.
The ideal situation would be to maintain a single "production" image
that could be used with either activation scheme depending on the
purpose of the machine.

Thanks in advance!