How do I change OPI Commnets in a PDF file?

Q: I have a PDF Form with an OPI Comment inside. The internal
structure is as follows:

        /OPI
        <<
            /1.3
            <<
                /Type /OPI /Version 1.3 /F << /Type /Filespec /F (/C/
Test/Hi-Res/001-A90841 ROM.eps) >>
                /CropRect [0 0 673 872]
                /Size [673 872]
                /Position [0 0 0 872 673 872 673 0]
            >>
        >>

I want to change the OPI path only (/C/Test/Hi-Res/001-A90841 ROM.eps)
to E:\test.eps.
How can I achieve this using PDFNet SDK (http://www.pdftron.com/
pdfnet)?
----------------
A: You could use the following Java pseudo-code as a starting point:

if (element.getType() == Element.e_form) {
  Obj opi= element.getXObject().findObj("Type");
    if (opi != null && opi.isName() && opi.getName().equals("OPI")) {
      Obj f = opi.findObj("F");
      if (f != null) {
         Obj path = f.findObj("F");
         if (path != null && path.isString()) {
                System.out.println(path.getAsPDFText());
                // Set new path
                path.setString("/C/Test/my.eps");
         }
      }
    }
  }
}