CCPregen

Compiled jars can be downloaded from Jenkins or CurseForge

Usage

Note that all coordinates listed below are given in blocks, not cubes. Coordinate conversion is handled automatically.

CCPregen is pretty simple to use. It adds a single command, unimaginatively named /ccpregen.
To pregenerate a 500³ block cube starting at (0,0,0):
/ccpregen 0 0 0 500 500 500

To pregenerate a 300 block wide+tall, 1000 block long tunnel in the nether:
/ccpregen -150 0 0 149 300 1000 -1

As this is a really simple mod, you currently can't have multiple pregeneration tasks running at once. Use /ccpregen_stop to abort an ongoing pregeneration task, and /ccpregen_pause and /ccpregen_resume to pause/resume pregeneration.