Dynamically add options to an Option Set using JavaScript

Javascript problems with CRM 2011 Update Rollup 12

We have faced problem for hiding the "NEW" button on lookup in CRM 2011 because It does not support following

crmForm.all.attributename.AddParam("ShowNewButon",0)


As Microsoft blogs(http://blogs.msdn.com/b/crm/archive/2012/06/21/microsoft-dynamics-crm-2011-custom-code-validation-tool-released.aspx) suggests that this .AddParam() is not supported in Update Rollup 12 of CRM 2011

So,we create a workaround for this:-

document.getElementById("attributename")._behaviours[0].AddParam("ShowNewButton",0);


This works fine cross-browser.