Well, I can't say for Melbourne, But Sydney Uni the UAI is around 96 - BUT, you must maintain a distinction average in the second and third year to proceed to honours!
That makes it pretty difficult I think. (You should could at the Melbourne Uni website yourself).
At Macquarie Uni you need an SNG of 70 which is half way between a credit and a distinction (and it seems like a good place to do Psychology if you aren't in a Go8 uni - ignoring that apparently MQ does have a good reputation in Psychology anyway, that exceeds Sydney Uni [but that's only based on heresay I think]). That is, it might not seem like you're just going there because it's 'easier'.
CSU would be easier to get into Honours because they only need a credit average in 3rd year, and half way between credit/distinction before that.
I'm not sure about UWS etc.. Again, you should look at some websites yourself.
