There are two versions now. One is the stand alone keyboard which doesn't replace your current keyboard.
The second version is flashable and it includes VOICE SEARCH! This one will replace your current keyboard. It is tested on Gingerbread and Froyo.
You can manually backup your keyboard apk via adb if you are confident what you are doing or I recommend a complete nandroid backup to make your life easier
Please read the new INSTRUCTIONS via the link provided