Hi charlie - if you read from about the 27 Feb, that's when I first started with Ann and I describe what we did in quite a bit of detail. The gradual withdrawal bit didn't actually start until after about two weeks of groundwork. That was so effective that, by the time I started withdrawing, we had pretty much zero crying. It was amazing.
I'd say 3.5 months is way too young to be looking for any sleep training options. Only She Who Must Not Be Named thinks babies that young can be shoe-horned into some kind of sleeping-through-the-night craziness. But the one you linked looks like she might be effective for a two year old. Why don't you start a thread on the sleep board to see if anyone's tried her?
Hear Ann said to me she doesn't know of any others that use the same approach she does, so I don't know if she could/would be able to recommend anyone else. Most other sleep consultants just cut straight to the behavioural approaches, which is exactly what never worked for DS.
Still getting one brief wake up most nights here, but he did an amazing unbroken 8pm til 7:30am on Saturday morning. I kept wondering why I had so much energy that day. He also almost pulled another 2.5 hour nap in his bed today which I managed to avert by opening his curtains and uncovering him at the two hour mark, which pissed him off no end but meant he had a nice long run around in the garden this afternoon, and we only started bedtime about half an hour later. I don't think Ann would agree with the later bedtime after a two hour nap, since she thinks that's what he should be doing, but I know DS. He'd have been swinging off his curtains for an hour if we'd stuck to his usual bedtime.
The project Ann's left us with is getting DS to walk himself back to his bed and get back in if he gets up at bedtime or in the night. He's got it down-pat at bedtime. If I hear him at his gate, I just say 'back to bed DS', without him even needing to see me, he goes straight back, I cover him up, and that's it. Night times are more of a work in progress. We've had a couple of nights of rage for 10-20 minutes before he'll throw in the towel, huff back into his bed, I cover him up and he's asleep in seconds without me needing to hang about. Ann's rationale behind it is 1) if he gets up in the night, he's welcome to do so as long as he does it quietly, then gets himself back to bed when he's ready and 2) he doesn't start relying on what is essentially a big cuddle whenever he gets up in the night (i.e. picking him up and carrying him back to bed), and potentially start waking up for more. We'll see how we go.
On a completely separate subject, how do you all go getting vegetables into your lot? DS is on total vegetable strike, here and at nursery. It doesn't matter how well concealed they are, they Do Not Pass His Lips. The closest we get are baked beans, chips 
and the odd pea if the wind is blowing in the right direction. Oh, he also loves the veg swimming in MSG in a Chinese takeaway 
Pasta sauces are my best bet, but he'll only ingest what's clinging to the pasta, so probably nothing that would constitute a portion size. Fruit is acceptable, vegetables are not.