1 - Locate the target packages (this works as scripted on the raw dtsx files)
2 - copy the script to an SSMS query window
3 - Place the full path to the first such package in the script (it's in the SourcePackage CTE)
4 - Execute.
5 - Save results in whatever form you wish
6 - repeat steps 3-5 for each package you wish to document.