Retrace,
Check out these 3 (very technical) articles, particularly part 3 and the room mode calculator. I played with the positioning of my M60s for 3 weeks to get the imaging and overall sound that I liked. After I read the thing, I took out the trusty tape measure. My speaker placement turned out to be within a 1/2 foot of where the mode calculator said the ideal spot for them would be.
Part 1
Part 2
Part 3
Room Mode Calculator
One last piece of advice. Pick one or two CDs of each type (hard rock, mild rock, country, jazz, and classical). Don't spend too much time trying to get any one CD to sound just perfect. Adjust the speaker position until you get a cd to sound pretty good, then switch to another CD. Make small adjustments at a time (1/4" to 1"). When I adjusted the positioning of the speakers to get a CD sounding perfect, the rest of them didn't sound quite right. When you get it close, switch CDs. Keep at it. The rewards are worth it. I now have the outline of the M60s drawn on the hardwood floor with a grease pencil so I can get them back where they belong in the event that I accidentally move them.
I wanted to take a survey to find out how much toe in people were using. The M60s sound best in my room with no toe in. Others indicate that they need to toe them in to get proper imaging. I sit 12' back from them, and they are within a few inches of 8' apart.
I have a 65" Mits RPTV between them. The TV itself will resonate and emit bass frequencies right out of the screen. Pushing the TV back about 2" cleared that up. It also messed with the sound of my VP150. I raised it up using some foam pads and tilted it down towards the listening position to fix that as well.
Best wishes, let us know how you make out,