Add this to include/jsfunctions.js
function getTime() {
var d = new Date();
var t_hour = d.getHours(); // Returns hours
var t_min = d.getMinutes(); // Returns minutes
var t_sec = d.getSeconds(); // Returns seconds
if (t_hour < 12){
t_ampm = "AM"
}
if (t_hour >= 13){
t_hour = (t_hour - 12)
t_ampm = "PM"
}
if (t_hour == 12){
t_ampm = "PM"
}
if (t_hour == 00){
t_ampm = "AM"
t_hour = 12
}
if (t_sec <= 9){
t_sec = "0" + t_sec
}
if (t_min <= 9){
t_min = "0" + t_min
}
return (t_hour + ":" + t_min + ":" + t_sec +" " + t_ampm);
}
And then call it with something like this added to the ADD or EDIT pages next to the input field:
<IMG style="CURSOR: hand" onclick="setTime(editform,'value_DepartureTime');" height=20 alt="Click Here to set the time." src="images/clock.gif" width=20 border=0>

If there is a better way to do it please let me know!