You have a much better chance to receive a helpful reply if you ask in the appropriate Acrobat forum; this is the Adobe Reader forum.
Also, a better description of your requirement would help; I for one cannot understand what you are trying to do.
If you want to cover 24 full hours in a day, then you will have a fair amount of coding to do. The supplied "Time" format for a text field starts at midnight, 12:00:00.000am or 00:00:00.000, and goes to just before midnight for the start of the next day, 11:59:59.999pm or 23:59:59.999. If you want to go form midnight to midnight then you will need to add scripting for the necessary formatting and validation.
Also the util.scand method does not do military time very well.