Convert native files to Grayscale pdf using PdfExport V851

I need to convert native documents (word file, msg file, jpeg, etc) to Pdf using outsidein PdfExport v851 but in grayscale. If the native file contains searchable text, that should remain the same in the exported pdf. All text colors, color images etc need to be black/white. I succeeded in converting to color pdf as-it-is in the native document, but could not convert to grayscale. Application development is in .NET (C#).