Forget the stock news app. Nice little interface, but it hogs battery and memory. Try RssDemon from the market. It's free and easy to use and much more customizable than the stock news app. If you like it, make sure you go into settings - accounts and turn off sync for the news app.
You can set your side key to launch rssdemon or set the search key + single keyboard key to open it. You're correct, the double tap on home key won't launch any third party apps, so that's a trade off. But if you use the reader all the time, long pressing the home key will most likely show it there also for quick access. I've just found the stock news app to be a memory and battery hog and rssdemon is a nice lite package when running.
