yeah, I had to think about this for a while when I first did it!
only one set of 2 wires will work, so just try them with a known working speaker and some small bits of cable wedged into the connectors temporarly.
the problem is figuring out which is +ve and which is -ve.
if you look at the bottom of the tweeter ( where the wires go into it) almost inside the pod itself you will see what looks like a tiny little red battery. this thing is in line with the +ve wire, from there you will be able to figure out which way around the wires for the door speaker should be because they meet at the tweeter.
OR!
another way is to look real close inside the connector on the speaker you remove from the door, it will be labled with a '+' but it is very hard to see, its
inside where the connector comes out of the door speaker.
OR!
the final way would be to look at this...
http://www.installdr.com/Harnesses/VW-Wiring.pdf and it should tell you!
and on the new speaker, the smaller terminal will be the -ve.