In order to make the Raspberry Pi use a Static IP Address with the wireless adapter use the following command to edit the interfaces file:
sudo nano /etc/network/interfaces
The settings below give a Static IP Address of 192.168.1.161, make sure you have connected the wireless adapter and got a connection to your router first.
auto lo iface lo net loopback allow-hotplug wlan0 iface wlan0 inet manual wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf iface default inet static address 192.168.1.161 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255 gateway 18.104.22.168
Obviously these settings are for my network, make sure you use the appropriate settings for your network.