Stick this in C: and add it to your user-startup with 'run<> nil:' in front, eg.

run <>nil: C:envtime s date

Instructions are in the program itself:

>envtime ?
Usage: envtime 12/s, S/s, Date/s, mdy/s
  12   = use twelve hour clock, default is off
  S    = Display seconds, default is off
  Date = Display date, default is off
  mdy  = use Month/Day/Year, default is Day/Month/Year
In Workbench Prefs add '%e time' to the screen title format

This program is not native, it was just a quick play with Amiblitz to see how
well it was working under OS4. if anyone wants the source just PM me (Severin)
on AW.

History:

0.01  First public release

0.02  Added external configuration files to set the day name to whatever the
      user wanted (never released)

0.03  scrapped external configuration in favour of using locale and saved 5k 
      in exe size :-)
      Reworked the main loop so the envvar is written as little as possible,
      with previous versions the envvar was written 5 times a second, now it's
      written once a second with the seconds option or once a minute without 
      it.