Put in shipping cost at checkout

[Scurry]

I need the ability to add shipping costs manually in a text box that will then be calculated into the total price.

 

This would be done from a separate "shopping cart" that our admin would only have access to. I have the extra cart setup, just need help with adding a field at checkout where we can input shipping charges manually.

 

I have looked at all the contributions and have installed many of the edit orders type of contributions, but we need to add the shipping as the order is being processed by our people.

 

Anyone help?

 

Thanks in advance.