How can I rename the shipping page in the checkout process

I am using Marketpress to sell tickets but these tickets will not be shipped to the customer instead they will just need email verification. I have changed the products to digital products which removes all the regular shipping fields and leaves me with just the required email address. Thats all perfect and what I want to happen but I would like to change the word "Shipping" from the checkout steps and replace it with something like "email". For Example instead of having the checkout steps looking like;
Review Cart » Shipping » Checkout » Confirm » Order Complete

I want it to look like;

Review Cart » Email » Checkout » Confirm » Order Complete

Thank You.