How do you ever get selected for an area of expertise not part of your resume?

Some pointers to get you started

• Understand the job and key selection criteria
• Find out about the employer
• Decide if you are qualified to do the job

Understand the job and key selection criteria

Study the position description, including the key selection criteria, along with any other relevant information you have collected. If you are unsure about any aspects of the job, call the contact officer during normal business hours. Their name and telephone number will be in the job details and they will be happy to answer your questions.

- See more at: http://careers.vic.gov.au/vacancies/key-selection-criteria#sthash.WTzyrSSr.dpuf

It can happen when you  are presented the new project and asked if you can do it and how

if you can analyse the need and anticipate the steps to make it and have  self confidence , you can convince your employer that you can handle it

By participating in a program like this one on Bayt.com. The program assists your skills based on your participation irrespective of what is in your CV.