Programming digital I/O pins on the NI myRIO-9100 for more quadrature encoder inputs

I am using NI myRIO for my robot PUMA 200 which has 6 motors. I want to use 6 encoder channels to obtain the positions of the motor axes. But myRIO has only 4 encoder channels. I watched the video "H-Bridge and GearedMotor Demo Walk-Through" (youtu.be/Q1UXVtVN-oQ, 6:01). At 2:59, panel of configure encoder shows the 4 encoder channels.

My question is if there is a way to program other digital I/O to get more encoder channels. Any help appreciated.