If your spouse wishes to seek employment in Australia, they will first need a visa with permission to work. This application can only be made after their arrival in Australia and after your study program has commenced. Please note DIAC's, which includes your spouse, and you and your spouse's dependent children.

Your spouse will also need to apply for

After obtaining their Visa with Permission to Work and a Tax File Number, they can begin searching for jobs.
See:

Useful links:

http://www.immi.gov.au/students/students/working_while_studying/index.htm

http://www.ato.gov.au/taxprofessionals/content.asp?doc=/content/64067.htm