samba - Jun 2010 - Forcing umask for "other users" , or remapping POSIX to ACL

Hello,

How can I instruct Samba, so public files (755/644) are not public anymore
when published by samba.

I publish some folders users ACLs. I want them to preserve the POSIX
persmission to 644, however, I don't want the files to be readable to
Everyone when accessed through Samba. So I want to either:

 * force an umask
 * remap the "Other" permission to a chosen group.

Can you help me on that?

thanks,

Franklin