You can remove the front speaker grills by carefully prising them out to reveal the screws that hold the speakers in. You do not have to remove door trim. I have never done the front tweeters in the windscreen pillers so can't help you there. The rear speakers can be removed once the plastic trim which the parcel shelf connects to and sits on is removed. The lug that the shelf clips onto on both sides has a screw through it, remove that, fold down rear seats and find other screws to remove the whole plastic trim. The speaker screws will be seen after the trim is removed. You need a very stubby phillips screwdriver for the screws as access to them is very limited as you will find out!
Hope this is of some help to you.
