I wouldn't bother applying for jobs through those sites as you have to check a box which says 'Are you eligible to work in Australia?' - obviously you aren't.
What I did is to use the sites to get details of jobs I was interested in and then got in touch with the recruiters directly to explain my situation and get my skill set across.
I ended up getting the job I applied for and now waiting for my visa to be approved by the government (its taken a few months for an IT role in Melbourne).
It's not impossible to get a job here, you just need to do it in a slightly different way to everyone else