There is a help function in the editor that should give most of the user manual. If you want additional information on how to add support for additional text-to-speech (TTS), see the file below. Note that the documentation has not been updated for the most recent version of Deig. Only minor differences in interface will be noted though.
Help/Tutorial: DeigHelp.pdf (4Mb)
Guide on adding TTS: DeigTTS.pdf (<1Mb)
Source code for creating TTS module: TTSService.zip (<1Mb)