[Users] Invoking guest os script, without guest having network connectivity?

I'm looking for a way to configure the guest networking(including IP) dynamically, using a custom script, right after VM creation. Is there a similar feature in oVirt as the Invoke-VMScript in of VMware's PowerCLI? It allows you to run a script in the guest OS, even before the guest has networking connectivity ( the host talks to the vmtools agent that's installed in the guest). Native KVM/libvirt option will be good as well. Thanks, Shlomi Invoke-VMScript reference: http://www.vmware.com/support/developer/windowstoolkit/wintk40u1/html/Invoke...