order configurable product when out of stock

I have to configure my magento store so that my customers can order configurable products when they are out of stock. Because these products are out of stock, they do not appear on the products page.

I did find a way to show them the products page (system-->configuration-->inventory-->Display Ou开发者_如何学Ct of Stock Products) but because the product is out of stock, the customer can't order it.

Anyone an idea on how to configure my site so the customer can buy out of stock configurable products?

I'm using Magento 1.5.0.1

In Configuration > Inventory an option exits to display products out of stock. This would be a good place to look.

EDIT: Also if you want the ability for the customer to purchase the product you need to allow products to be back ordered in the following configuration tab.