Have the button change to "Checkout"

Hi,

Instead of going straight to the Cart after clicking the "Pre-Order" button, the button instead changes to "Checkout" and a link shows up, "View Cart (1)" on the right side. This is the same as when we have stocks and the button shows "Add to Cart". It doesn't just jump straight to the cart.

Reason for this request is that we may launch a product that has several colors (artist paints) and customers may buy more than 1 color. It's just too much hassle if they keep on clicking back to product just to add more variants (colors).

How to go about this?

Thanks.