Javascript ICal Recurrence Rule implementation

On our project we have a simple limited implementation of the Ical recurrence rule functionality. It is based on jQuery and HTML form elements. The existing JavaScript code needs to be extended with more options (see below). Here is the demo what we have already http://g4j.laoneo.net/demo/gcap/create-event.html.

New functions when Monthly:
- On [first/second/third/fourth/last] [mo/th/we/tu/fr/sa/su] of month
New functions when Yearly:
- On [month box] [day box] of year
- On [first/second/third/fourth/last] [mo/th/we/tu/fr/sa/su] in [month box]

This are the basic ones, perhaps you will find more interesting combinations.

Some Ical rrule examples can also be found here http://www.kanzaki.com/docs/ical/rrule.html.