Hi iniaro and welcome to SP. Not a lot of climbers doing the south wall of Aco that are on this site that I know of. For up to date information try contacting the folks at Natural Renewable Resources that oversee Aconcagua Provincial Park at http://www.aconcagua.mendoza.gov.ar/ if you haven't already.

There is a specific protocol that South Face climbers must follow such as a requirement for carrying a VHF radio, checking in and out and they are suppose to supply you with weather updates on a daily basis. There's a PDF file you can view online (under Norms, Activities of High Risk) but I don't know how much of it is actually applicable.

Good luck.