Yes, CM roms at least 10.1 and 10.2 have ad-hoc patch. I can connect my HP Touchpad running CM 10.1 nightlies to my N9.

But I would still be interested in making N9 wifi hotspot in infrastructure mode if possible.

Edit: I don't think stock AOSP 4.2.2 and 4.3 have ad-hoc support