Can I get the sign-up form to display on pre-order products?

A pre-order product is a product that has inventory and is in-stock. Our form won't show on in-stock products even if they are set as pre-order. If inventory runs out, then our form would display.

There is also a technical limitation of a script that runs externally to your theme. The script has access to a very limited subset of product data on the product page. It receives information if the product is purchasable and/or in-stock, but does not have access to know if the product has the pre-order flag set.