I've had 11 toranas :)
If you are _really_ stuck, buy the tyre outright, then use a rubber mallet to get it on the rim (if you don't know how to do it, I'll make the genuine offer to do it for you - I'm north of the essendon airport, and would only have time to do so on the weekends. Done 'right' with a rubber mallet, it'll mount the tyre onto the rim, without damaging it (manual tyre levers aren't usually a good idea on alloy rims)
OK so that gets the tyre on there, but doesn't push it out onto the beads to seal.
The only way you are going to do that (though I do have a compressor and am more than willing to try it, but think it won't work, just too much of an angle to push the tyre beads out onto the rim) - anyway - the only way - more than likely - you'll be able to mount it is like this :
http://www.youtube.com/watch?v=d7bN8WPok9E&feature=relatedhttp://www.youtube.com/watch?v=z8w3zhgX92UYou don't have to use hairspray - wd40 works ok'ish, and very small amounts of carby cleaner spray work very very well but I don't know what effect the carb cleaner solvent would have on the tyre rubber itself.
If you did that, you might then be able to take it somewhere and they'll balance it, but you might find it just as hard to get someone to merely balance the already fitted wheel/tyre combo.
From the workshop's point of view, there is inherent risk, and even if they warned you of the risks but still fitted it, and something happened, they'd be legally accountable for it