To enable "non-US" channels on your wireless card under BT4 (and the new mac80211 stack):

You will need to download a few packages, and programs to enable use of the upper channels of the 802.11b/g spectrum:

apt-get install python-m2crypto libgcrypt11 libgcrypt11-dev
download crda and the latest wireless-regdb, both of which can be found at:

Next, extract the wireless-regdb contents:

tar xvjf wireless-regdb-2008.11.17.tar.bz2 (latest file when I tried this)
and copy the file "regulatory.bin" to /usr/lib/crda/

mkdir /usr/lib/crda
cp regulatory.bin /usr/lib/crda/
Next, untar the CRDA tarball you downloaded:

tar xvjf crda-1.0.1.tar.bz2
change dir to the resulting crda directory, compile and install:

cd crda-1.0.1
make && make install
Copy the file regulatory.rules found in the udev subdirectory under crda to /etc/udev/rules.d/85-regulatory.rules

cd udev
cp regulatory.rules /etc/udev/rules.d/85-regulatory.rules
Now, you should be able to set your country code using iw:

iw reg set ##
(where ## is the ISO Alpha2 code for your country such as DK for Denmark)

This should open up all the channels that are usable in your particular country.

Use iw to see what frequencies/channels are available:

iw list