Toilet vent pipe placement

Not a direct answer to your question, I know, but have you considered using an air admittance valve instead of a traditional drain waste vent? That way, you need no building envelope penetrations at all.

and where does it fit in the system? FYI, i will not have an attack space.

This can get you started on AAV's, but be aware that they are illegal in some areas. http://www.studor.net/ Check their legality with your local building department before you even look at AAV's. If they are illegal, see a local, reputable plumbing business who will know your codes for proper sewer venting.

You need a plumbing stack that vent out the top. Sewer gas need a way to vent. An AAV is not a vent. It is closed in 1 direction in the it doesnt let sewer gas in to the home but does allow air in the system to allow a fixture to drain.

A good use of an AAV would be for a sink in a kitchen island. You dont have a vent going up but you still need to let air in to facilitate drainage.

You need a plumbing stack that vent out the top. Sewer gas need a way to vent. An AAV is not a vent. It is closed in 1 direction in the it doesnt let sewer gas in to the home but does allow air in the system to allow a fixture to drain.

A good use of an AAV would be for a sink in a kitchen island. You dont have a vent going up but you still need to let air in to facilitate drainage.

Matthew, There may be some rare exceptions, but I've never heard of a building or plumbing code that allowed air admittance valves to be used when a conventional alternative was available. They have prescribed limited uses in islands and renovations. Certainly for new construction vents are required. What was your rational for trying to avoid plumbing vents?

Don't know what code you're under, but per the 2009 and 2012 IRC you do not have to go through the roof, you can go through a wall, see http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_31_par015.htm