You know, come to think of it, my H6 Outback 2002 model is the first car that I DIDN"T take the door trim off and replace the standard speakers. So I can't help you there, although it shouldn't be hard.
I can't remember completely, but I think I started to take them off once and got the clips and screws off and then changed my mind (yes, and my new mind works better).
I think, from memory, there are two plugs on the door arm rest that you take off and then remove the screws. You then have to lever up the window winder plate and disconnect the wiring plug. Next is the door latch opener. I think it has a small plug in the centre that you have to remove and then there is a screw under that.
This is from memory, so it could be a little hazy!
Losiho, maybe able to help in this department as he has your model, I think.
Oh, I also forgot about the tweeters. You need to lever the tweeter cover off. This is simply done by levering it away from the door. Should come off easily. It's then a matter of levering the complete door trim away from the door proper by popping each plastic clip from around the door and lifting up and off.
I haven't touched my door trims, but I think from memory Peaty over at Scooby mods might have a thread and pics devoted to speaker upgrades and removing the door trims - but I'm not sure which model / generation the article and pics were written for.
I checked Scoobymods, and there doesn't seem to be any articles about removing door trims
from memory there are 2 screws in the handle lift the window switch up and unplug then there are some sort of press type attachment which you carefully use something broad and flat between the panel and door and lever outwards, this is what I recall seeing the panel beater do when he repaired a dent in my rear right door
If it's like some other cars, the trim clips are "sacrificial" meaning they break when they're removed.
I need to open up the front passenger door (not original, see my gallery) because now when I stick the key in the lock, it simply spins around.
I already had to re-align and tighten the door latch in the sill; it started to come loose, and the door would not close enough to shut off the door-open indicator on the dash. But that was an easy fix.