No doubt you will be told to use that tweak app that I just can't figure out (the instructions are as poor as its implementation, in my opinion). http://wiki.maemo.org/N9QTweak#Tweak_CC:_WLAN_MODs
Tweak CC: WLAN MODs Activate/Deactivate Adhoc at startup for USA users as well as allowing you to change the WLAN MAC address.