magento - Edit in RSS Feed for product feed

Hi, We got a RSS feed we would like to have customized a bit for magento 1.7 shop, so it only shows products which are on our frontpage (meaning that you will have to sort by specific product attributes - which is start and end date, which is product specific). you can see feed here: [login to view URL] Feed also needs to be actived for our german shop - .de -