I have done fair a bit of work with villaboard and Harditex, the 3 methods described work ok but as mentioned using power tools does a tremendous amount of dust and even when you are done cutting it is everywhere, the very fine dust is a pain to sweep of your pavers, the plants are suddenly white, swmbo complains etc..
My preferred method is the fibro cutter, it is reasonably accurate but the edges are not as nice as with a diamond tipped blade, anyway Villaboard is either joined or tiled over so the edges are not really important and a high precision is generally not necessary.
Just put 2 pieces of 50x50 under your sheet and cut it on the ground.
I'd lend you my cutters but I guess Sydney is a bit far for you

they cost around $50 and many small hardware shops rent them.
PS: Don’t forget to prime your villaboard before tiling, makes it much easier to tile.
Hope that helps
Jack