Just wanted to update that succeeded in creating the Citation manager - http://formidablepro.com/help-desk/citation-manager-add-on/

The form fetch the XML data from pubmed collect it in a table and publish a post.

this it the main code I wrote:

The following code can be used to conditionally change the default value in a field, depending on a parameter in the URL. Change 25, 26, and 27 to your field IDs. Replace 'pass_entry' (in two places) with the parameter name in your URL.