Can I use the DTM Debugger / Switch-Plugin with a self-hosted option like library download or FTP?

The DTM debugger / switch-plugin can be leveraged for self-hosted options if the staging and production libraries are hosted on the same server. If the libraries are hosted on separate servers, then a different method such as Charles Rewrite would be used.

For more information on using Charles Rewrite, the documentation is available here: http://www.charlesproxy.com/documentation/tools/rewrite. Essentially, the rewrite would be set up to replace the entire production script with the entire staging script to facilitate testing.