If you are interested in the standalone tool, please scroll down to the bottom of this article. There you find the download link and a quickstep guide for installation. Also note that JASS-2 comes with the ready installed grid-align tool and it should work out of the box. (ALT G in edit mode)
What is the problem …
Sculpties are encoded using a 2d-image containing a 32-bit image map, where each axis is encoded in an 8 bit value. Thus There are only 256 valid vertex positions available along each axis. This property of sculpties is equivalent to using a size dependent grid for each axis where the bounding box of the sculptie defines the grid spacing. It is not straight forward to make your model manually align to these constraints, although some clever solutions to the problem already exist:
