Are the ADAU1761's microphone inputs available on the A2B Module EVM?

Yes, the pins from the ADUA1761 are brought out to a set of holes near the board edge.

There are also nearby ground and Vcc holes as a small amount of passive components must be added to power the microphones. Details of how to connect up microphones are covered on the ADAU1761 data sheet.

The default ADAU1761 program uses the line in and headphone output jacks. You will need to modify the program to select the microphone inputs and adjust the gains to match your application. Details of loading new ADAU1761 programs as part of the A2B network boot are found in the Analog Devices document: " A2B SIGMASTUDIO USER GUIDE,"AE_09_A2B_SigmaStudio_UserGuide.pdf. This document is included as part of the A2B software kit supplied by Analog Devices.