Thanks, Emad.
I was also advised by a job agency in Aus to contact the Board directly first, rather than just sending out the application. The agency said they don't have first hand experience of direct registration for applicants like me.
I am going to feel very unfair if the Board replys me I am not elligible for that type of registration, because Canadian graduates may register in WA even if they fail the national exam in Canada.
Anyway, I may try to go through NZ registration to get the Aus registration if the WA Board rejects me.
Pico