We recommend the quality Australian books from the Golden Beetle Books Spiritual Syllabus series sold through Spiral Garden. To get started there is the comprehensive title A Steiner Homeschool by Alan Whitehead. Alan has decades of experience in Steiner education.
Some more useful contacts for Steiner homeschooling curriculums include:
For the correspondence course run through Candlenut Steiner School near Cairns in Far North Queensland, email Nila Chambers or email the school.
An Australian email support group for Waldorf (Steiner) homeschoolers can be found here.
Steiner Schools in Australia site - lots of useful contacts and resources.
Waldorf Homeschoolers - information, advice, resources.
Waldorf Without Walls - curriculum, support, advice, resources.