Apply shipping without the shipping screen
You can automatically set the shipping method on a cart (e.g. by an ajax call) at any point by POSTing to commerce/cart/updateCart - You just use an input with name shippingMethod and and the value you supply is the handle of your shipping method, e.g. `ground'.

Where you do this is entirely up to you, but note depending how you handle/implement this, changes in the cart contents &amp; addresses can invalidate shipping methods, so you'd typically do this at some point after your cart index page...