You're screwed. How did you let this happen? You sit there and complain about ALL the free time you have and how BORED you are....and now this???
Gleim only takes one serious day, with a 12 pack, or two easy days with a six pack each...
But to answer your question. Your best bet is to find a CFI DE who could sign you off without fanfare. Don't go to some dumb flight academy, you just need a ride with an appropriately blessed DE. They are out there, guys who can sign off CFI's can do it.
Find out in advance what they are looking for and see what recent CFI apps had to go through. Rent a plane (you'll probably lose your CFI-ME cause of this) and do a couple of hours doing comm mans and IFR stuff. Treat it like you were a new hire at Skywest.
I can't be too hard on you. This once happened to me. I did the ride in a 172 and I don't remember it being much of a deal. He told me he couldn't sign me off for the CFI-ME since we didn't do it in a twin, but when he was looking at my old certificate as an example of how to do the new one, he wrote down "CFI-ME". I didn't know whether to say "hey, you screwed up" or just let it ride.
I decided to let it ride...
DE727UPS, CFI airplane, instrument, and multi-engine. Plus a couple of type ratings....