ImageEn supports all standard TIFF compression formats, plus some non-standard like ZIP and Deflate.
Using TImageEnMView you can convert from a format to another (G4FAX in this case) writing:
ImageEnMView1.MIO.LoadFromFile('input.tiff');
ImageEnMView1.MIO.Params[0].TIFF_Compression := ioTIFF_G4FAX;
ImageEnMView1.MIO.Params[0].BitsPerSample := 1;
ImageEnMView1.MIO.Params[0].SamplesPerPixel := 1;
ImageEnMView1.MIO.DuplicateCompressionInfo();
ImageEnMView1.MIO.SaveToFile('output.tiff');
You can also use a TImageEnView (or a TImageEnIO + TIEBitmap) to process a page at the time, using SaveToFileTIFF for the first page and InsertToFileTIFF for the others.