If you go to this thread:
You can see where I put new tweeters in my doors, and if you look carefully, there are 6.5" drivers in the doors. I would post more detailed pics, but the images I took from the construction process were on my brother'* camera, which he hasn't been around for a while. Basically, a Dremel tool is all you need.
I've ordered another set of components to install in the rear doors as well. Will post when I get that job done, however my car is in the shop due to a collision, so this may be a while before I can tackle it.