Silky--- 
All the warnings about what not to do so your hen doesn't go broody---do the opposite!  :O)
sooo Everyone says gather your eggs regularly, well, leave eggs in the nest (if you could get them I think I would use fake eggs---do they have them in OZ where you are?  Gosh, do they call them Farm & Station Stores there like here they are called Farm & Ranch---or are they just feed stores?  But I digress.   
So a nice nest, lots of eggs to stimulate her--- lots of food a good environment so her hen mind thinks that it would be a good time and place to raise a family.  I saw one person say that extra calcium will support the hormone structure that makes a hen broody, sooooo make sure there is lots of oyster shell and or crushed egg shells for your hen. 
You cannot make a hen go broody, but maybe you could nudge one that is so inclined to become broody.  Good luck!