Simon,
Just follow the steps listed on the
http://fubar.gr/hacking-the-flir-e4/ site directly but use the 2.11
upgrade and hack files Xavier64 linked you to. The fubar site says its for 2.3.0 only, but the exact steps listed on that site work with the files Xavier64 provided on a flir that has firmware 2.11. I did the hack less than a month ago on a new Flir E4 that came with the 2.11 firmware already on it.
Edit: The fubar site has a section on switching the flir to RNDIS mode. This worked for me, but when I first did it, my computer and flir froze up for a while until I finally decided to unplug the flir from the usb, and as soon as I did, every thing unfroze. Then when I plugged the usb back into the flir, it was in RNDIS mode and it finished setting up with an IP address. The main thing is if it freezes during this step don't be afraid to unplug the usb to get it going again.
Edit2: Sorry, I didn't see that you were already on firmware 2.11. You don't need to grab the 2.11 upgrade file that Xavier64 linked to, because you are already on 2.11. You just need the 2.11 hack file. Then when following the fubar guide, in the section Prerequisites->6. Script Pack where it says to download the 2.3 hack pack, you can skip. And in the following steps where it says to use the 2.3 hack pack, you will use the 2.11 gotten from Xavier64's link instead. Everything else is identical to how the fubar site says to do it. The files/folders in the 2.11 hack pack are named exactly the same as the ones in the 2.3 hack pack, so its literally just following the instructions directly.