Quick intro, I'm a sparky who's lived here in WA for over 9 years and holds a WA "A" grade license, Contractors license and Open data license. I don't believe dual citizenship will have any bearing on getting a license. When I started on the road to emigration, I had to get my trade recognised by TRA, once completed they would only send the cert to an Australian address, which is where your friend might come in handy.
Once I had the TRA cert (Electrical Mechanic), I had the option of doing a 5hr practical exam and then a multi-choice rules and regs exam, or night school for 3 months. I did the former.
The Office of Energy will be your best source of info, as it is they they issue your license. The last bulletin, I got from them stated something along the lines of having to serve approx 1 year with an Australian company to get experience, before issuing a license.
Here's a link they may help.
http://www.innovation.gov.au/Skills/SkillsAssessment/TradesRecognitionAustralia/AustralianRecognisedTradeCertificate/Pages/default.aspx