Very User friendly:
Chunk Pregenerator has a lot of features that make it very friendly to the users, such as:
Complete Documentation of each Command,
Auto Completion/Suggestions on Command-arguments as needed to provide guidance,
Improved logging that is color coded and structured to display...
Forge 1.8.9 is required, drop this mod in mods folder located in .minecraft directory.
Then in your launcher, select forge installation -> Click edit -> Scroll down -> Click "More Options" -> Scroll down -> in JVM Arguments at the beginning add "-noverify" - Click Save and you can now launch it...