Using the KVM API

You can pass raw qemu command line in the libvirt XML. This is an equivalent of '-vnc :30,tls -k fr -no-fd-bootchk':

<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
...
<qemu:commandline>
<qemu:arg value='-vnc'/>
<qemu:arg value=':30,tls'/>
<qemu:arg value='-k'/>
<qemu:arg value='fr'/>
<qemu:arg value='-no-fd-bootchk'/>
</qemu:commandline>
</domain>

The VNC option doesn't need to be presented as a command line, I just left it as an example.