Apart from just screwing speakers into their 3 standard screw holes, what other ways have people used in the falcons?

I don't exactly see it as an accousticly sound way of mounting a speaker to be honest - especially if you spend over a few hundred dollars on a new set of splits.

Do you mean without using screws? a car isn't an accousticly friendly environment/shape anyway...

Nothing wrong with mounting with screws!
If you dont, what else is gonna hold them there?
Im guessing if you that worried about it, uve pulled your doors apart to sound deaden them and try to make them close to air tight n used a good foam speaker mount ring under the driver; also good to have something directly behind the speaker in the door, not just empty space/window..

Use the Screws buddy, cant see why not.

Bingo! I'm not opposed to using the screws- not at all. I was thinking more along the lines of mounting something to the holes and mounting the speaker to that.
I haven't taken the doors apart for a while - so i can't remember what it looks like, but I was pretty sure there was some kind of open space and no baffle as such.
Would a thin MDF baffel help when sound proofing then?