I found a script made by Bin4ry over on XDA which allows the rooting of many Android devices running ICS or JB without unlocking the bootloader, and is confirmed to work with the LG Optimus G (very similar to the N4). I couldn't find any mention of he Nexus 4 in the original thread, so I'd like to know whether or not anybody has tried this method with their Nexus 4, and if so, does it work? Help would be appreciated, the script is available from the above thread on XDA.
I searched the thread for "Nexus 4", "E960" and "Mako", and it returned no results, which is why I posted here.
That's good.. I would be sure to post the question in that thread though, where the author can address it and other users may be able to help as well.. you are just more likely to find some reliable advice asking it there if you haven't already. Let us know what you find out about it for sure.