I have always used a scoring tool available in the tile tool area of the big box stores. It is the same tool you use for concrete backer board. It has a small carbide tip like the tip on a circular saw blade. For straight cuts you can score lines on both sides using the scoring tool and a strait edge and then snap it along the line. For curves I used a Remington abrasive grit jigsaw blade. You can also get abrasive grit hole saws. I don't think a utility knife would cut it . Good luck.

Greg