How do I carbonate a drink that originally isn't carbonated without altering its taste or the process taking more than a few hours? I've seen some methods that use yeast, but that requires about two days and the taste changes, so that won't do. 
Wilds of Russia? If you have dry ice, just adding pieces of it (chopped small) to your drink will work to some extent. Here's a vid: How To Make Soda With Dry Ice Be aware that not all dry ice is food grade. If no dry ice, you can get by with sodium bicarbonate (baking soda) and vinegar (acetic acid), or some other acid. Just mix the two chemicals, and bubble the resulting gas through your drink. Here's an Instructable, w video: Carbonating: The Cheap and Easy Way. It'd be easy to improve on the kid's method, for example by adding a bubbler stone, but the general principles are sound. Either method will cause some change in your liquid's taste, as you're lowering the pH by generating carbonic acid, but that's true of any carbonation scheme. 