Depends what type of business - some require long waiting periods for permits, etc, others can be done very quickly. We did a full incorporation in about 7 weeks. There is A LOT of paperwork - I would definitely recommend getting a good lawyer who can explain everything clearly. PM me if you want my lawyers name - he is good and has done most of the expat businesses.
Attorney in BA - you said "neither the shareholders or directors need to be Argentine" - While true, the director of the company must be a RESIDENT of Argentina (therefor if the OP doesn't have residency, s/he would need a local partner).
Star - are there specific questions I can answer for you?
My 2 cents - as I mentioned - having a good lawyer and accountant is essential IMO. My accountant is worth every penny we pay him as he not only does books but assists with employee matters (setting up bank accounts, etc)
assuming you will have employees - it is a PITA and there are lots and lots and lots of rules and regulations that are required if your employees are en blanco. I swear, I pay more in taxes and such than I do in their salaries. And no, I'm not really joking.
Opening a bank account is a PITA and again, this is where I would say having a local partner will be invaluable.
There are lots of steps you have to follow to do the incorporation but generally, the process is a lot more painless than I thought it would be.