A simple question that is not so simple to answer. What technologies did they use on their journey? Can we trace the settlers lineage using dna sequencing now, or will we ever?
Australia was settled 40,000 to 60,000 years ago.
They arrived by sea during period of glaciation when portions of Australia were still joined to the main continent.
According to the below linked wiki page this makes them some of the worlds first mariners.
All in all, based on the fact that it was 40,000 to 60,000 years ago it would seem the technologies used to settle were some form of ancient boat. (I'm guessing no 1st class luxury cruise liner)
Once they arrived they settled into a hunter gatherer society. Here they developed basic stone technology which they used in their day to day lives.
Additional Info can be found here.