Allow passing parameters to XML script file so that I can maintain one general script for many sites

Below in the examples are the parameters that would change from site to site.  Other than these parameters the transformation XML script is identical across sites.  With parameters, it would be simpler to maintain these files. • Host, Database and DefaultPIServer for both the DataSources and the Writers                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               • Value for ValueFilter