If you want to go this way, I suggest this form, which then just needs to be sent to the share registry: http://sraa.asn.au/forms/form23.pdf
I can't say for sure about Centrelink. However, I expect the asset would be valued at their last traded value as Centrelink don't have any means to assess the prospects of the company while suspended. For example, most companies come out of suspension and trade normally, and others may rise or fall after suspension.
As you mention Centrelink , you may find it simpler to "sell" the shares (you actually pay for the transfer) to that company that takes over non-trading shares (not sure if it's fine to name them here). This removes them from your possession, and therefore removes that as an asset, if this would have a material effect on your situation.
