Thanks for your query to the Ireland Reaching Out message board.
You may have to search for the assizes records in either the National Archives of Ireland at:
or at the National Archives in the UK at:
You might also consider using the British Newspaper Archives as a source. They have Irish newspapers in their collection. This is also a fee-paying site as is the Irish Newspaper Archives.
Have you tried looking through the Ireland-Australia transporation database? It is available at the link below:
The very best of luck with your research!