Steve, technique Question?

Yes, but how did you manage to train your fingers? Every time I tru to use my ring finger, It moves my other finger enough to where I block the strings. Also, I get wrist burnout VERY fast!
 
Try to practice standing up if you're used to it sitting. Or try sitting down with the bass on your lap if you feel your wrist tweaking standing up. See a doctor if niether of these works!
You can do independant finger exercises all day long instead of waiting to force it to move full force on the strings. It'll go, just takes time and starting out slow.
 
I am playing with three fingers as well. As I started to do, I did not know that there were others using this technique as well (until I saw a Dream Theater Video).
But to talk about playing the bass; The most important thing is to warm up your fingers or you'll have some really big problems. The next and also very important thing is to practice loud (using your amp), because the tone produced by your ring finger should sound similar to the tone produced by your other two fingers (otherwise you have some kind of triplet feel in a 16th note rhythm). Just try to find the right position for you hand (it should not be hurting, of course).
As already said, start slow. Play some easy and slow stuff, using your ring finger and the other fingers. And be aware that you use one finger after the other, all the time! (best way; Ring, middle, index). There's also a technique everyone is able to do; Attack the string with all three fingers, one after the other, starting with the ring finger, and that as fast as you can (just three notes, but they should be very fast, like this three Basskicks we all now from many bands). This is very easy, but I don't know how to describe it because my english is not that good. It's something like knocking with your fingers on a desk or something.
Just one more thing; If something is hurting, stop practicing immediately! I sometimes did not, and now I still have problems (about 1 and a half year ago).
You can also practice to a metronome, it will help you getting more indepence for your ring finger. just play some stupid 8th or 16th notes to a slow tempo. But there's still something you should pay attention on; When you are playing the E-String (for example) and then want to play the A-string, be sure that you don't interrupt the ring-middle-index system. If you are playing for notes on the E-string, the last note was played by the ring finger. The next note on the A-string should be played by the middle finger, and so on.