To start..ALIMBO. I didn't do my initial CFI with them. I did it through my university the long slow way. I echo what CFIjim said about getting quality instruction for the initial. Even doing only the add-ons with ATP I'd recommend some hardcore studying on your own before you go in. As Amish pointed out, they send you a booklet and you need to know it front to cover. HOWEVER; this book is only about 20 pages so there is very very little material covered. So, memorizing should not be a feat of strength. Most of it is Seminole systems and the company's flight profiles. There is, I believe, ONE page that covers IFR regs. I have no issues with folks who do their add-on CFI ratings in the "get rich quick" courses. What I DO have an issue with is people who do them and come out thinking they're Gods gift to flight instructing. As long as you know you were trained to pass a checkride profile and not to be a proficient instructor you'll be alright. Just be diligent and hit the books on your own. Remember when your a CFI you're responsible for you, your student and THEIR future passengers. The one thing you'll learn quickly is that the PTS is a joke. Teach your students to be REAL pilots not just pass the checkride. Be their mentor and gain their respect. Don't sign them off just because they can meet PTS standards. Make them pilots...not "aircraft flight control operators". If and when your student goes on to be a flight instructor they can only teach his or her students what it is that they know and everything that THEY know came from you. See the chain? Don't be worried about soloing your students. Remeber that everything that student knows came from you. So, if you're not confident in your student...you're basically saying that you're not confident with yourself. Hence going back to discussion of getting quality instruction for your initial CFI.
As far as my II/MEI experience goes...I actually did my MEI and II add on at seperate times. Where I was teaching IFR students were scarce for some reason at the time; but, there were quite a few multi students so I went to ATP and knocked it out in two days. At the time I had about a year and a half of CFI experience under my belt and about 150 total multi. So I felt pretty comfortable about going the "quickie" way. I recall the training and checkride to be a non-event. Basically fly the twin and run through the maneuvers from the right seat. I went in for the II about a year later and it was pretty much the same deal - fly the plane under the hood from the right seat, fly some approaches, examiner flies some approaches while you teach her.
I'm going to be interested in the Bowling Green location. I'm from the west burbs of Chicago so all my previous stuff with them (with the exception of the time building out of Seattle and up and down the west coast) was done out of the Chicago/Aurora location which they've closed down. I think I'm staying at a Super 8 down there. There are also some hamptons and marriotts in the area from what I understand. If the Super8 is a dive and I end up with bed bug bites tonight I'll probably go somewhere else for the remainder.
Second...CFIjim. I'll be sure to post how the ATP goes. I'm looking forward to getting this done.