Hi,
As I said in a previous message, you will have to modify the checkout / show_block_cart view file via the menu Display>Views for this.
In there, you have the product data in $cart->products
It might not contain all the data you need. So you might have to run some MySQL queries, not sure.
The product name header is displayed between the tags <!-- NAME HEADER --> and <!-- EO NAME HEADER -->
So you'll have to add similar code for each extra column title header.
Similarly, the product name is between the tags <!-- NAME --> and <!-- EO NAME -->
So you'll have to add extra td tags after it for each extra column with the corresponding value to be displayed.
It's just a normal HTML table with a header and rows and columns so it should be fairly easy. The hard part might be the loading of the data, if some data you need is not available in $cart->products.