JSCalendar can be used to add to date input fields a button that let that user choose a date using a pop-up calendar. For the time being configurability is limited. Essentially, you can use an ERW type (jd) to specify that a JSCalendar button should be added to a date attribute (if JSCalendar is not configured, you will not get the button). JSCalendar should work on all browsers supported by ERW
First of all, you must download and install JSCalendar (or higher) and set a suitable configuration variable. Then, there are several ways to customise JSCalendar. For the time being, you can only configure the look of the calendar by setting a suitable style sheet to be loaded. The default ERW style sheet shows how to load a style sheet.
The warnings given for HTMLArea are valid also here. Be very careful, in particular, with translations, which are selected automatically.