Since there isn't a direct approach to this issue, another 3rd party tool needs to be used. The process is called PDF Printing which involves in installing a virtual printer driver.
You can use CutePDF Writer. Obtain the installation from the following link: http://www.cutepdf.com/Products/CutePDF/writer.asp
Once the virtual printer is installed, open the SPX file and then go to File > Print and select the CutePDF Writer. Once the process has started, a dialog window will appear asking you where to save the PDF file.