It's totally possible, and ANY number of wires can be identified this way.
The only difference is whether the number is odd or even.
If you have an even number, as you state, you start at one end and tie pairs of wires together.
Go to the other end, and find a pair that are tied together using an ohmmeter. Mark one of them #1 and tie it to ground. Mark the other #2.
Find another pair, and mark one of them #3 and tie it to #2. Mark the other #4. Find another pair and mark one of them #5, and tie it to #4. Mark the other #6. Seeing a pattern here? When you get all done, #1 will be grounded, 2 & 3 will be tied together, as will 4 & 5, 6 & 7, 8 & 9, and so on.
Make your one return trip, and use your meter to find the pair that has one wire grounded. That's #1. The wire it was paired to on that end will be #2, and it will show continuity to another wire, which will be #3. The wire #3 was paired to will be #4, and it will have continuity to another wire, which will be #5. Seeing another pattern here?
It's hard to visualize this with nothing but the written word, so take a short piece of scrap conduit and some scrap wire and try this sometime at home. Once you see how easy it works, you'll be amazed.
If you start out with an odd number of wires, you start by grounding one wire, marking it #1. Then you pair the wires up as stated above. Go to the other end, and find #1, which will have continuity to ground. Find another pair of wires that are shorted, and tie one of those to #1, marking it #2 and the other #3. Find another pair and mark one of them #4, tiing it to #3. The other is #5..etc.etc.etc.
Make your return trip, and the wire that is shorted to #1 is #2. The wire #2 was shorted to is #3, so #3 is identified. #3 was shorted to #4, so it can be found......
Once you try this a couple times with the scraps you'll see it works, but it takes patience. But it can be done, with 3 wires, 20 wires, or thousands.
Now for another brain-buster:
You are in a large commercial building, and you know there are 3 sets of lights fed by 3 circuits. But you cannot see the lights from the panel, nor the panel from where the lights are. Make ONE trip between the lights and the 3 breakers and correctly identify all three circuits. For this, let's say the lighting circuit numbers are 7, 9 and 11, and the lights would be called East, Center and West. No radios, no helper, no meters.... just you and shoe leather.
:grin: 
