The bacode hasn't been designed to be editable in all that way. You can controll it's width, silence zone, aspect ratio of the moduls, the error correction level and color. Everything else is dynamically generated depending on the input data, which hast to be a string. Binary data isn't supported.
Try the following settings when calling the renderPDF417 function.
/** Begin to rendern PDF417 code
* @param sInput String: String to encode
* @param iECC Integer: Error correctio level -1 (default automatic), 0 (low) bis 8 (high)
* @param fRatio Float: Aspect ratio of the modules (pixel) (default 2.0)
* @param oPDF417 Objekt: XFA-Object, that represents the code
* @param fReserve Float: Whitespace around the code
* @param fSize Float: Width of the code
* @param sUnit String: Measurement for whitespace and width (mm, cm, in or pt)
* @param sColorDark String: RGB color of the dark pixels (default "0,0,0" = black)
**/
if (!this.isNull) {
XFAUtils.renderPDF417 (this.rawValue, 4, 3, this.resolveNode("Barcode"), .254, 58, "mm", "0,0,0");
}