Most courses can be entered via the full-fee route, in which you pay the entire cost of the course upfront (although you can take a loan out from the government and pay it back through the tax system). The UAI cutoffs for full-fee are normally a few points below the HECS cutoffs, sometimes more.
If you go to the UAC website and look up the courses you're interested in, they'll show two cutoffs - CSP and DFEE.
CSP = Commonwealth Supported Place = HECS place.
DFEE = Domestic fee-paying = full-fee place.