Is rooting 4.2.2 really this complicated?
My further investigation indicates that the Nexus 4 Toolkit isn't the best one to use - in fact it doesn't seem to work at all with 4.2.2.

Instead, the Nexus Root Toolkit seems to work well with 4.2.2 and is basically a one-click installer. Download from the linked page and run it; it will do the rest by itself and/or give you simple instructions when needed. 

Update: I've just completed the rooting process with this tool. Worked well and was simple enough. Note that after completing the process, I had to download and install the Superuser app from the Play Store - this step was not completely evident, but simple to do.