I don't think removing your door panels would have anything to do with your warranty. If that were true changing speakers would void it. So I seriously doubt it.
Now for removing the panel on your car....
the "special" tools look like small plastic pry bars, crow bars & wide spatula looking things. A tape covered small flat screw driver will often get the job done. Be gentle. If you break a clip, they are replacable, if you scratch your interior, you'll cry!!
