We have this request in our system for possible future inclusion so if you would like to be automatically notified if this feature is added then you can open a
Support Ticket. As 4StarGen mentions it can be done with custom statistics.
This guide covers the basics on custom statistics creation and
this guide gives a deeper walkthrough. The latter was written for PokerTracker 3 but the techniques all apply to PokerTracker 4, the interface is just slightly different.