Applying Inherited Permissions with chmod

I have the file TestFile in the folder /TestShare shared on an ACL-enabled volume. If in Workgroup Manager I apply a read-only acl for group testgroup and propagate the permissions, the resulting ACE is

0: group:testgroup inherited allow read,execute,readattr,readextattr,readsecurity

The closest I can come to replicating this at the terminal is
sudo chmod -R +a “testgroup2 allow list,search,readattr,readextattr,readsecurity,file_inherit,directory_inherit” /TestShare

The ACEs now are

0: group:testgroup2 allow read,execute,readattr,readextattr,readsecurity
1: group:testgroup inherited allow read,execute,readattr,readextattr,readsecurity

Because of the -R flag, the new ACE is uniquely applied to everything contained in /TestShare instead of inherited. This is different than what Workgroup Manager’s “Propogate Permissions” command does. Is it possible to precisely replicate the behavior of “Propogate Permissions” or “Apply Inheritance to Selected File” using the terminal? Neither the File Services ot Command Line documentation explains this.