Chimera

Are there any variables that can be used in the search/replace post processing script? I have it currently replacing ";LAYER:" with "M117 Printing Layer:" so that the LCD on my printer shows the current layer, however I was hoping to figure out a way to make it say "M117 Printing Layer {a} of {b}". Is this possible? I'm using Cura 3.1 and I have a Wanhao i3 Plus clone (Monoprice Maker Select Plus).