I have gone through the pain of trying to use those commands and use
other available cron clients for Windows to find they are expensive, or
have bugs and are not stable. So I wrote a very simple yet powerful
script that handles all the basic functionality of Cron. It has been
stable and used in production for about a year. The source code is in
Python and you can read it, it is a simple page. I have also created a
version for Windows with an installer that doesn't even require Python
installed in the target machine.

You can find the project here:
http://sourceforge.net/projects/pycron

Emilio.