What have you done so far trying to install them? You can cut the door panel some to gain width. I had to resort to a 3/4 inch wood spacer that screwed to the door and cutting the door panel out around the the wood spacer.
I have completely removed the back cover plastic rain cup, and will be installing foam baffles to make up for it.
I have studied the door, and to increase the inner diameter of the front speaker orifice, requires a bit more major surgery. The door hole as is now, is nice and structurally stiff, if I go into it, I will lose that and have a thin single sheet of plastic to mount the speaker on.. and I have no garage, wood router, or set up to go into it...
I could use my spacer ring as a guide, and try to dremel it out, and maybe mount the spacer ring underneath the plastic... but there is that bottom metal beam in there too...
Sorry, once and Engineer... always and Engineer...
Unfortunately, I had the same issue as you. My door speaker was wide and deep. You just may have to attach the spacer to the door and not the door panel. It is more work, but on the positive side it is a more solid mount.
With the 3/4 inch wood I cleared the beam and the window while rolled down. I was also able to put the stock speaker cover back on. Let me see if I can dig up a pic or two. PM me your email adress and I will send them to you.
Also, dont bother with the rear speakers. It is really not worth it. Just put in the fronts and a good sub. Rear fill is highly overated. I dont use them in any of my installs. Search the net and you will see a lot of people that feel the same way.
One other thing is you may have an issue with the 8 gauge cable. I think that amp can take up to a 4 guage. 8 may be a little on the small side.
Last, but not least...you can grab line outs off the radio before the factory amp, though they are balanced line and will need some form of conversion. You may want to check out JL Audio's HD line of amps. They accept balanced line in and are supposed to perform way better than the Alpine PDX line. That will simplify your install some because you wont need the LOC anymore.
I did my install with an Audio Control Four.1 EQ. That unit can accept balanced line in and output a regular line out. The great thing is I have absolutely no engine noise in my system at all. That is a very hard thing to do on a Honda.