Jscalender module come with Jstools package in drupal 5 you can
download drupal jstools package from the drupal.org site.Jscalender
uses the jsCalendar javascript library, like using a special CSS class
called via #attribute in the form element array to convert textfields
into jcalendar enabled.



The jcalendar module uses hook_form_alter() to look for textfields with
the add-jcalendar class, I had to use something different than
jcalendar which is used later on the generated form elements by the
jQuery code.