My original requirement was to figure out how to pass a multiselect picklist from a calling object to a new object.  I have a custom object that has several fields I need to pass to a new Event object. I used to do this with an scontrol that created a URL querystring with all of the parameters.  This works OK, but is not going to be supported forever. SFDC Support suggested replacing this with a VF and apex solution.  My original attempt used a VF page with a page level Action that called a method in my controller to build a new pagereference back to the new event page.  This works great, except for the multiselect picklist.  The multiselect picklist is passed in the URL by duplicating the same field id multiple times, once with each value of the multiselect picklist.  Support says that using the field ids (gathered using firebug on the standard page, is not supported, and suggested that I should create a custom version of the event view, and leverage a shared controller to pass the data.

I am working this solution, but have two areas that I haven't figured out.

How do I replicate the "Recurrence" section of the standard page?

How do I replicate the "Add Invitees" section of the standard page?

Anyone have any ideas on how to solve the original problem, or the new ones?  Any sample code would be appreciated.