Just to give a further heads up on this, just trawled through most of the pages and found the following info
"That's odd - I have what I am told is the most recent Alfa Service News on Brera wheel angles in front of me (which I sent to SR with the idea he might publish it for the rest of you) and the toe settings are much smaller than AutoData says. It varies with rim size: 16 is -0.45, 17 is -0.50 and 18 is -0.55 all +/-0.5 mm."
"the settings are basically 1mm +/- 1mm toe-out on the front (so you can set to 0mm)
and 3mm toe-in on the rear."
"I had the fitters replace with the exact same type of tyres (Pzero R18s) and set the toe to zero. After another 5000 miles the new tyres are barely worn at all, and appear even across the whole tread "
Post 677 - Provides some useful values http://www.alfaowner.com/Forum/3320441-post677.html (159 / Brera / Spider tyre wear issues - VIP - Revised Information)
"Front should be set to parallel
Rear, make sure it is within manufacturers settings, toe and camber."
So the consensus seems to be
Toe set to parallel/0 on the front
Toe set to manufacturer levels for toe - Although someone mentioned 3mm toe, does that fit within the manufacturer ranges?
As post 677 seems to suggest that rear toe (each side) should be between 0.06 and 0.20 (presumably 0.06 would be preferred here?) and then total toe of between 0.12 and 0.40. Is it the total tow that should be 0.3? and thus around 0.15 each side?. Sorry if these questions are self explanatory.