V-Magine Installation configuration

Hi, I'm having some issues with my V-Magine installation. The network adapter I use in Hyper-V has to be configured with a VLAN tag, and for the network to work in a proper way the MTU has to change from the default 1500 to 1400 on the guest OS. Because of this, the installation fails, would there be a way to set the MTU for the installation? If this isn't possible, there are two other way which should fix the issue. - If the installation wizard could use internal adapters, then a NAT interface could be configured. - If I could set the external adapter to be a legacy adapter, I could then use a different IP. Also, I need to change the timeout found in "/usr/share/openstack-puppet/modules/nova/manifests/db/sync.pp" from 300 to 600 before the installation starts. Would appreciate any help with this, thanks :)