Invoking a script inside a KVM guest, before networking is available?

view story

http://serverfault.com – With VMware's PowerCLI you can invoke a script inside a guest, even before the guest has network conenctivity, using the Invoke-VMScript Cmdlet (requires vmtools to be installed). Is there a similar mechanism available for invoking scripts inside KVM guests, before networking is available? I need to for post-deployment customizations. As a workaround, I thought about mounting the disk image and chrooting, but i'm looking for a more 'scriptable' and straight forward way. Thanks. (HowTos)