How do I upgrade the version of Hyper-V Integration Services that SCVMM 2012 R2 offers to VMs?

Folks -

The Hyper-V integration services/Guest services are found on each host in the c:\windows\system32\vmguest.iso file.  Unfortunately, I've found that the contents of that ISO are *not* what SCVMM uses to install in a VM during deployment from a template.  Rather, the integration services seem to be sourced from the SCVMM server itself.

There is a newer version of the integration services that has been released with a hotfix and I'm finding that when I deploy new VMs, the latest integration services aren't deployed - even though the vmguest.iso file on each of my hosts has been patched to the latest version.  I need to figure out how to update the integration services on the VMM server and therefore the version that it offers and installs on newly deployed VMs.

In prior versions of VMM (e.g. 2008 R2), you could simply swap out the contents of a folder with the new integration services.  I'm not finding it that simple on VMM 2012 R2 and would like some input.

How do I update the integration services that VMM 2012 R2 installs on VMs either during a new deployment or through a right-click "Install virtual guest services" operation?

Thank you.