So much fail...

OP, we are not trying to affend you in any kind of way. We are truely trying to steer you in the right direction. Just by listening to some of the things you are suggesting, and mad methods, it sounds like ghetto riged every where. No to be so harsh, but bro, seriously. I highly advise not placing those tweeters back there. If money is the issue, than sell what you have currently, and buy something else. OR, just wait until you have the right amount of money to upgrade the right way. You have to understand, certain drivers are designed to only play certain frequencies. If you splic your tweeter with one of your door speakers, that means the same signal your door speaker is getting, is going to go to your tweet. THAT is what is wrong with youre idea. You don't want your tweeter to play those lower notes, AT ALL, especially at high volume. As it will only result in spending more money, and most of all, abusing equipment that will fail due to user error. No matter the cost of the driver(s). I will create a list of suggestions.

1. Sell current and all speakers/tweets
   
2. Then you could buy two sets of these www.parts-express.com/pe/showdetl.cfm?partnumber=269-097
   
3. Then you could power them with this http://www.parts-express.com/pe/showdetl.cfm?partnumber=269-188
   

Just to , OP you're asking "which hammer is best to drive 3" deck screws into my dry-wall" the answer is "none". The fact that you're replacing blown speakers and already have 4 tweeters and are not happy is telling. I have a Challenger which is much bigger on the inside and the 2 tweeters from my component set on 50 watts rms could be the loudest and most irritating part of the system if I didn't EQ them DOWN. You are going about fixing your problem the wrong way, and buying things you don't need is the biggest waste of money there is.