I have not ever tried it. Years ago, at my trainer's stable, I helped nasally vaccinate 30 or so minis and full size horses for strangles and we both thought at the time, the nasal vaccine for that was a much bigger pain in the butt than an injection would have been. The delivery system was via a fairly long nasal tube. Now, I do not recall if we snipped it shorter for minis or not, but I do remember it was hard to administer swiftly and most of the horses were very uncooperative when it came to letting us stick it up their noses. The delivery for this vaccine, though, may be more straight forward and easier.
Good luck!