I think it works for other commands but couldn't find that one.
It's not clear what you're referring to here.
What works for other commands?
You can have the time announced in one of the computer-generated voices supplied with OS X by going to
System Preferences ->
Date & Time ->
Clock, checking the
Announce the time checkbox, and clicking the
Customize Voice... button to change from the currently selected voice to another one. I think you'd need to find a third-party solution to use your own voice, though.