The addXML utility is automatically built when you install and configure LAS. The easiest way to run it is to use the shell script provided ($LAS_HOME/bin/addXML.sh). We are no longer distributing addXML as a separate software bundle. If we ever need to distribute an update between LAS releases we'll do so via a "beta" LAS release.
The addXML utility can scan a netCDF data source, like a file or an OPeNDAP aggregation URL or it can scan an entire THREDDS catalog or sub-catalog. Finally, there are a number of options on addXML that you can use to control the configuration created and make your LAS installation work well for your users.