Amie's right, it is really room dependant.
In a perfect room, which nobody has, there should not be any toe in required because of their smooth off axis response. Walls, other than holding up the roof, are a bad thing :) Quite often in most rooms it's a trade off - great bass vs. depth of image.
First try them not toed in, on the same wall, facing your listening position, about six to eight feet apart (depending on how far back you sit) and give that a try. Ideally, with the side walls an equal distance from each speaker.
Sit in the sweet spot, listen to a good, stereo recording that you know well and try and gauge the following; is the vocalist dead centre?, are the highs sweet or edgy?, is the bass full and rich?, does the sound seem to come from beyond the speakers?
Those are the criteria I use to try and find the best spot.
You'll want the speakers as far enough apart that the vocalist is coming from dead centre but not too far which will create a hole or smear in the centre image.
If the highs seem a bit edgy, it can be reflections from the side walls causing phase distortions (reflected sounds arriving at your ears later than the original). Start toeing them in in small increments until the treble becomes smooth. Depending on the room, that can effect the bass too though.
Try bringing them out from the rear wall as much as is feasible and listen for when the sound starts coming from slightly behind the speakers to bring out the depth and transparency. Toe in or toe out will effect that too.
The key is to experiment as rooms are a variable that's hard to quantify. But that's all part of the fun though, eh?
