It looks like the method in the first post of this thread does not work for adding Chinese (zh and zs) to W760a (AT&T branded). I followed the procedure exactly, except deleting lng.dat files as they are not there. ZH and ZS still do not show up in the list of languages after reboot.

Has anyone successfully added ZH and ZS to their AT&T branded W760a phones? If so, how did you do it? Thanks very much in advance!