This one is great. I don't have the time to do it since I'm not incredibly skilled at programming yet, but it should be all that hard to make an autohotkey script that can do this for you a little bit more in the background. It's not often you have your pandora tab, or even your browser active.

So the script would basically say, for each hotkey: store current active window. Store current browser tab, switch tab to pandora, send key [whichever command this is]. Now switch the tab back to the stored tab. Now switch the program back to the stored program.

This way, you could send these hotkeys, probably with a modifier of some sort, while still keeping pandora in the background and it would be less disruptive. If I have to use my mouse to go activate pandora to dislike/like a song, then I might as well just use that to select the button. So if someone wants to go ahead and script that I wouldn't complain.