I have wlan0 as my default device.
Look at this file: /etc/sysconfig/network
BOOTPROTO=static # I added this
And in /etc/sysconfig/network-scripts/ifcfg-wlan0:
# Broadcom Wireless 4311
After inserting these files, connecting with encryption was enough. Negotiation went automatically I didn't even had to execute dhclient wlan0...
You should be able to understand this by reading (I think, you seem quite experienced). If you have anymore questions, post it