[rhelv6-list] virtio-scsi disks on rhel 6.3?

[Gianluca Cecchi]

Hello,
virtio-scsi support is claimed as a tech preview in rh el 6.3 release notes.
But walking through them and tech notes I don't find any "official"
way of using/testing it.
In virt-manager I don't find any option...
And also on rhn I don't find any reference in kb or tech briefs.
Is it supposed to be used only with "virsh edit"?
What is the syntax to use in respect with fedora17 based
virtualization hosts for example?

Thanks in advance,
Gianluca