I think the only way to do this is to use the workflow call-out hooks to execute some code that creates the calendar entry using Web Service calls. There is a Twitter example of a workflow call-out posted in the customization area of this site.

http://community.kablink.org/ssf/a/c/p_name/ss_forum/p_action/1/action/view_permalink/entityType/folderEntry/entryId/2705

Thanks Peter, for your response.

Firstly how do I deploy this custom action, I mean in which directory, is there any default directory for the same or can i place it anywhere?

Secondly how do i access different data elements in the workflow entry, for instance , there is a user list, now how do i get all the names selected in it.

I believe this is documented in the admin guide. But the answer is that you put all of your custom jsps in the "ssf/WEB-INF/jsp/custom_jsps" directory tree. The custom_jsps directory (with the exception of the "samples" subdirectory) doesn't get overlayed during upgrades.