[libvirt] How to pass -no-kvm-irqchip to KVM/QEMU guests

Hi, experts, I am using libvirt 0.10.2, and doing some tests against guest IO performance. Can I have a way to pass -no-kvm-irqchip in libvirt xml files to qemu-kvm? I did some search in google, it hits: http://www.redhat.com/archives/libvir-list/2009-September/msg00495.html But it seems it does not work on CentOS, after I used this wrapper script, qemu-kvm will crash.. and I did not find libvirt upstream solved this problem, is there anther way to solve this? Thanks a lot.