The latest firmware the Pineapple now has a fantastic amazing new feature - built in the drivers for various USB wifi chipsets. Primarily the Ath9k driver from what I can tell so far. In order to use this guide you'll need a supported USB wifi dongle and a MKIV Pineapple. I used a TP-Link WN722N (Also works well with reaver). Before you buy a wifi adaptor please google the model number to determine its chipset.
Supported USB Wifi Devices:
A small list of devices running Ath9K - http://linuxwir