I approached Chenard author Don Cross with two questions:
1. How can I disable the internal book of Chenard?
2. How can I set the hash table size?
In answer to this he also asked some questions:
1. Do you know the command that will be sent from WinBoard to turn off openings?
2. Do you know the WinBoard command for setting hash size?
I am a bit surprised at these questions as I thought they were engine specific commands which have nothing to do with WinBoard. Can anybody help me?