With the Unices available to me...
...Tru64 and Mac OS X/Darwin/BSD/callitwhatyouwill both have good date doco, with clear descriptions of the format required to set the date.
Rant
On: On a completely different tack, the man page for ssh on Tru64 is simply appalling. It's presented in 80 columns, no matter what. Not a single paragraph break in the whole thing. It seems descriptive text is there, but everything else was ommitted. Take this bit for example, which would seem to be a description of command line options, except there's no clue as to what those options might actually be:
Specifies
the number of password prompts before giving up. The argument to
this keyword must be an integer. Default is 3. Specifies
whether to use password authentication. The argument to this
keyword must be or Note that this option applies to both protocol
version 1 and 2. Specifies the port number to connect on the
remote host. Default is 22.
Ick. ick. ick.
Rant
off:
Phew. I feel better now.