In my search for a browser that can be controlled by just the arrow keys (a remote), I found that Opera actually does support that very well:
Opera: Tutorial - Use Opera without a mouse
You can just select links by pressing SHIFT + ARROW to go to the nearest hyperlink.
I tried it and it works great! Maybe a plugin can be made for the opera browser, like this plugin is for FireFox.
Edit:
I found another great thing:
Opera Mobile emulator for desktop - Dev.Opera
Opera mobile for Windows!!! Maybe that is even easier!
I can confirm that it works great with my remote. Now it has to be integrated somehow in MediaPortal..
-geometry 1280*720 -notouchwithtouchevents -fullscreen -url #browserlink