Thank you for taking interest in our software and welcome aboard!
> I would like to sell items by the yard with the minimum qty to be
> purchased being 1/2 yard. Currently I can only go with whole numbers.
> What all is involved to allow this to be possible?
X-Cart doesn't support fractional qties, it needs to be customized accordingly and we have done such projects actually (sorry, cannot give samples other than listed at http://www.x-cart.com/featured_clients.html
But I come up with one idea for you: you say you want to sell by yards and 1/2 yard of the minimal possible. What if you specify in your web shops that a "1 item" is 1/2 yard? Thus 2 items will be 1 yard, 3 items 1 and a half yards, etc. You can replace label "item" with "1/2 yard" in X-Cart front-end so it will items for X-Cart code but 1/2 yard for your web-site visitors.
Does it work for you?