You can import the image directly as a template and then edit the template to add nics and cloud-init configuration.
(This way you can easily setup multipile preconfigured VMs from it. You don't have to use run-once for cloud-init).> Does the image correspond to the qcow2 one downloadable from
> http://cloud.centos.org/centos/7/atomic/images/ Yes.
>
> or does it contain any customization already related for deploying in oVirt itself?No, its the exact same image.
HTH,
Barak Korren.