I'm not 100% sure on all the requirements. Somewhere on the centrelink website it will say. this (http://www.centrelink.gov.au/internet/internet.nsf/payments/youth_allow_iat.htm?) and this (http://www.centrelink.gov.au/internet/internet.nsf/factors/index.htm) seem to be the most useful.

HOWEVER centrelink are quite full of lame, and one person may approve your application and another deny it. It's quite the luck of the draw coupled with persistence.