Add product SKU/Name field to paypal form

[JohnBerringer]

I trying to add product (or multiple products) sku/name to paypal form so when customers purchased product and i got paypal confirmation (Or when i look paypal recent transaction.) i see what they purchased.

I figured out you need to put it into Payment Extra Info section on PayPal module, but can someone provide piece of code for that. How can i get product SKU's from clients shopping cart and group then for that field?