for moment I thought it was possible, but no it's not(it is still shareadParameter) and this stupid forum don't allow to delete posts
Ha it is possible, I just made it. 🙂
this is how :
Transaction trans = new Transaction(doc);
trans.Start("Project Parameter");
//first you need to create Definition group
DefinitionGroup defGr = //your metod to create it, my is to long to past here but there is a exemple in SDK
ExternalDefinitionCreationOptions option = new ExternalDefinitionCreationOptions("nowe", ParameterType.Text);
// here we create Definition
Definition ed = defGr.Definitions.Create(option);
//chose in witch category schould it be
CategorySet cs = new CategorySet();
cs.Insert(Category.GetCategory(uidoc.Document, BuiltInCategory.OST_PipeCurves));
//you can bind it as instance or type, I did with Instance
InstanceBinding bind = new InstanceBinding(cs);
// with it you made a new project parameter
uidoc.Document.ParameterBindings.Insert(ed, bind);
trans.Commit();
---------------------------------------------
-------------------------------------------------------------
--------------------------------|\/\/|------------------------
do not worry it only gonna take Autodesk 5 years to fix bug