Overriding qemu.conf libvirt-qemu user per-domain

[Pascal Proulx via Users]

Hello,

How can I override the libvirt-qemu user defined in 
/etc/libvirt/qemu.conf using a per-domain (virtual machine) override 
using the domain XML definitions? I can find qemu arg overrides but not 
this and I may have missed it.

Thank you