Hi @charlie64,
A warm welcome to the Bunnings Workshop community, it is fantastic to have you with us.
It is possible to use a jigsaw with a tungsten carbide blade such as this Diablo Tungsten Carbide Jig Saw Blade to cut curves in fibre cement materials.
Trace the profile of the corrugated iron onto the Hardie Plank and then carefully cut it out with your jigsaw.
Make sure you wear a mask, eye protection and hearing protection as it will be dusty and quite loud.
Let me know if you have any further questions.
Jacob
