I made this mod for the German Story HD Wifi. When you select the book shop, it shows a Web Portal instead, where you can select the actual book shop, or various other sites, or enter any URL. The portal itself is a HTML file you can edit to your liking, so you can put in your own links.
I could probably do the same for the US model, but I don't own it, and I have yet to determine if the setup is identical to the point that the firmwares are interexchangeable so I could freely switch between German and US flavour of Story HD Wifi.
Of course I could just do it blindly and hope it actually works and doesn't brick your stuff. Any volunteers?