See this guide
for the basics on custom statistics creation and this guide
for a deeper walkthrough. The latter was written for PT3 but the techniques all apply to PT4, the interface is just slightly different. You'll want to pay particular attention to the columns for Call Steal and Fold to F CBet as you'll basically be writing a column that has both the steal called and the CBet faced (for the opportunity column) or folded to (for the times column).