ok,

Tried the ifconfig wlan0 down. It didn't seem to work.

But I think I've stumbled upon the neatest solution. The way to solve it is to stop the icd2 service. When this is stopped it stop asking for connection and just uses the usb one. Seems neater then unloading modules too.

to disable the service as root type:

/etc/init.d/icd2 stop

to start again when you've finished

/etc/init.d/icd2 start