HOw to add an external wifi antenna to my MacBook?

Errr… you don't. Is there any reason why you couldn't extend the range of you base station rather than the MacBook. Most decent base stations have the ability to add antennas to extend their range. Else, you could add a 2nd base station and connect it via WDS.

For reference, he is refering to latching onto other's computers and routers and such, and he can't really go and install antennas on their gear, they might get a BIT suspicious, but I can't answer the original question either...

There are 3rd party companies that offer what you're looking for. Pick up a copy of MacWorld or MacAddict and look near the back for the ads.

- Dan

You can't add any antenna on you built in Airport, but if you insist to having antenna for your wardriving activities, then you should but a new usb 2.0 wireless adapter (check for compatibility with intel and os x) that provided a dedicated antenna, you can then buy an extention cable with male thread and female thread on each side, and you have a longer/rectangeble antenna.

Just install the driver and choose it on your system preference instead of your built in airport (turn airport off)