Joomla Virtumart - Disable Checkout per Product Category

By federal law, I am required on some of my products that they have to be "Call to Order". Is there a way that I can disable the checkout process or at least the payment processing for specific categories on my site and instead are asked to call customer service to complete the order?

Workflow ==> User finds a product he/she wants, customizes the color and other attributes as needed, they then click continue or checkout but at this point the order is sent to customer service and the customer is then asked to call customer services to complete the 开发者_运维百科order.

But that same client and make and complete their order on the site for other products such as part and accessories.

You can make a product say call to order by simply enabling the inventory check and setting the product inventory to 0. However, that also prevents the user from adding the item to the cart. You'd have to hack the core significantly to achieve the workflow you specify.