Yeah it is very similar to the early entry scheme for une .... but i believe it is a little harder.
With une it is very much a principles recommendation ... with csu it is more based on you and you must submit with the application your trial HSC results. Along with a small piece of writing saying why they should accept you into the course you are applying for.
When you put in you preferences to UAC and you apply for an early entry make sure that is high on your preference list (1st would be most advisable) ... and also there are some courses that you are unable to apply for in the early access program.
hope that helps