How to work around read only DynaPDFFieldExMBS?

I wanted to ask others MBS DynaPDF user.
DynaPDFFieldExMBS seems to be read only, how to workaround it?, i wanted to make a ObjHandle for the “AddActionToObj” MBS DynaPDF.

Wanted to make something like these :

Dim objHandle As New DynaPDFFieldExMBS
objHandle.FieldType = 0
objHandle.FieldName = ListJavascriptField.CellValueAt(o, 1)
createJS = pdf.CreateJSAction(ListJavascriptField.RowTagAt(o))
ActionReply =  pdf.AddActionToObj(pdf.kotField, pdf.koeOnMouseUp, createJS, objHandle)

Tried code above but getting

Example.btnEditJavascript.Action, line 115
The constructor of this class is protected, and can only be called from within this class
Dim objHandle As New DynaPDFFieldExMBS

To create a field, please use the various field creation methods.
e.g. CreateTextField, CreateButton, CreateCheckBox, etc.