To change the pin mode from analog input to digital input, you can use the PRT0DM[2:0] registers. PRT0DM2 is for bit2 in the drive mode, PRT0DM1 is for bit 1 in the drive mode, and PRT0DM0 is for bit 0 in the drive mode. You can lookup the drive modes in the Technical Reference Manual under Figure 6-1 "GPIO Block Diagram". I assume that you want to change the drive mode for a port 0 pin.
In the chip editor, you can configure Port0, pin0 to analog input. You can also connect Port 0 pin 0 to the CapSense shield pin. At run-time you can switch between the drive modes of High-Z and High-Z analog for Port 0 Pin 0. Do let me know if you face any further issues.