Change tax rate based on attribute selected

Just wondering if anyone has a simpler solution to this.. before I try taking an axe to the code.

I am setting up an online shoe store. In Ireland, children's shoes are tax free, wheras adult shoes are taxed at 21%.

So for every product in the store I need the tax rate to change depending on which attribute (shoe size) is chosen by the customer. For example if they choose size 2 it will be tax free, but if they choose size 8 it will be taxable.

Yes I know I could set up two different products (taxable shoe sizes + tax free sizes) but that's very messy and not ideal.

Thanks,
David.

OK I have belatedly seen this thread which I suppose answers the question.. although the news is not good.

http://www.zen-cart.com/forum/showthread.php?p=668833

That was back in January though so maybe someone has found a solution?

I notice that oscommerce seems to have a contribution to do exactly this task, although I have not yet tested it. https://www.oscommerce.com/community/contributions,6072

Cheers,
David.