show calculation

Hi! just tested the Plugin and it works great!
Now I would like to show the calculation on the checkout page, like:
Delivery: Handling 10,00 EUR + 20 km * 2,00 EUR = 50,00 EUR
I have some php skills and I’m not afraid of editing the plugin myself, if could you give me a hint, if that is possible and where to start.
Thanks!
martin