You need to download the following .inf file to your desktop.
Right click and 'save link as' tetherxp.inf
; Google Nexus 4
%AndroidDevice% = RNDIS.NT.5.1, USB\VID_18D1&PID_4EE3
were added by me to get our Nexus 4 to work with USB tethering.
Plug in your USB cable to the Nexus 4 and your PC.
Turn on Tethering through the Nexus 4 Settings->Wireless->Tethering&Portable Hotspot->USB Tethering
You should get the 'Found New Hardware Wizard'.
Chose 'Install from a list or specific location'. Click 'next'.
Choose 'Don't search. I will choose the driver to install'.
Chose 'Network Adapters'. Click 'next'.
Choose 'Have Disk'.
Browse to the desktop where the tetherxp.inf file should be. Click on tetherxp.inf and click 'open'. Click 'ok', then 'next'.
Agree and continue as required. Note that while USB Tethering is on, you may not be able to use your PC wireless or wired connections. You will need to turn of Tethering on the Nexus 4 to do that while it is plugged in.