Hi, You need to upload those resources in Images & Description section of your app in distribution portal. The icons on Kindle Fire Tablets are dynamically pulled from Amazon Apps. Side-loaded apps cannot use this feature. Once you've submitted your app and it's live on Amazon, your app's appropriate icon will automatically be displayed. Thank you for writing to us.
Thanks for the answer, but I believe side-loaded apps CAN use this feature. Hi-res carousel icon is successfully pulled from HDPI and XHDPI icons. So I would like to know on what basis Kindle Fire chooses it. Using Amazon Apps is not an option for me for some reasons.