Documentation is available here [https://imagej.net/plugins/bigstitcher/].
Most of the functionality used in BigStitcher is implemented in the multiview-reconstruction package.
A GitHub repo for massively parallelizing certain BigStitcher tasks on the cluster or cloud (or to simply run it from the command-line) can be found here [https://github.com/PreibischLab/BigStitcher-Spark].