Hi Emma,
The ProtXMLViewer is under the cgi-bin/ directory of the image. However, the version in 6.2.0 does not have the command-line capability of exporting protXML to TSV. We introduced this feature in 6.3.0, and will be available once we produce the related image. (well, after fixing some bugs and releasing 6.3.3, soon).
Do note that if using the viewer interactively, you can export to TSV via the File & Info tab of ProtXMLViewer.
We can gladly help convert a few files for you if you are able to share those; just contact me directly if so.
Thanks,
--Luis