What I did was unscrew those speakers and take them out. Unplug them from the wiring and then secure the wiring so it doesn’t rattle.
Drop the speaker wire into the space in the dash and catch it at the bottom. This may be a little difficult, but not if you have small hands.
You’ll need to make some sort of bracket to hold the tweeter up. You can use mdf, plywood or something like that. I had some left over foam from the door speaker spacers, so I cut the template from the old speaker and then cut a hole big enough to put the tweeter in.
I then attached it to the dash with a couple of bolts and nuts (and washers so it didn’t pull through the foam) and no rattles, but it sits nicely in the foam bracket.
Then, once the wire has gone through to the bottom, you can mount the crossovers.
Obviously, the crossovers will send the treble to the tweeters and the rest of the sound to the door speakers. Put the wires from both into the cross over and then connect the speaker wire to the amp (or head unit, if applicable).
I chose to mount the crossovers where the factory amp would go if my model had one. But, anyway the unit isn’t going to rattle is fine.