Hi,
It is not possible to do that without hacking the code.
I see that you don't have any shipping methods on the checkout actually.
What you could do is use the shipping methods as week selector. The user would add the blocks he needs to the cart and the quantity for each block. Then on the checkout instead of shipping methods, we would select between a number of weeks. Each week would be a shipping method.
Then, you would set a basic price for each product and a weight of 1kg. Then, you would create 5 shipping methods for each week:
1week with a min weight of 0 and a max weight of 1.5 and a price of 0.
1week with a min weight of 1.5 and a max weight of 2.5 and a price of 5$.
1week with a min weight of 2.5 and a max weight of 3.5 and a price of 10$.
etc
then the same for the 2 weeks,3 weeks, etc
During the checkout the weight of the cart will be calculated. Since you products would always be 1kg, only 1 instance of each week shipping method will be displayed with a price corresponding to the number of items in the cart.
Would that meet your needs ?