KVM problems with Vt-d and wireless adapter

I'm exploring the use of Vt-d with KVM. I'm running the following setup

Processor:        Intel Core2 Duo P8600
KVM version:  88-r1
Host :             Gentoo 32 bit, 2.6.30-r4
Architecture:    i386
Guest VM:      CentOS 5.3, 32 bit, 2.6.18-128 kernel
Command:      kvm -hda vdisk.img -boot c -m 384 -net nic -net user -pcidevice host=03:00.0

I'm trying to pass through to the VM, the Intel 5100 wireless adapter. I have ensured that
a) the BIOS has Vt-d enabled
b) the Gentoo kernel was compiled with IOMMU features enabled
c) the driver module for the iwlagn is blacklisted on the host
and d) I run a script to unbind the device and bind it into pci-stub based on the HOWTO assign device with Vt-d in KVM

If I run the above command, I get 2 sets of error messages

assign_irq: deassign: Invalid argument
assign_irq: deassign: Invalid argument
assign_irq: deassign: Invalid argument
assigned_dev_update_msi: deassign irq: Invalid argument
assigned_dev_update_msi: deassign irq: Invalid argument
assigned_dev_update_msi: deassign irq: Invalid argument
assigned_dev_update_msi: deassign irq: Invalid argument
assigned_dev_update_msi: deassign irq: Invalid argument

If I add the -no-kvm-irqchip switch, then the assign_irq: deassign: Invalid argument messages go away. On the guest I get messages from the iwlagn module that it attempted to write the nicrocode to the device. Each time it fails, and it just happens to try 5 times. On the host, depending on options I get errors like:

irq 17: nobody cared (try booting with the irqpoll option) <-- tried this but nothing changed followed by a call trace
then a message that it is disabling IRQ 17

Any thoughts as to what I'm missing? More information needed?

---Michael J Coss