Typically, it involves copying the files to a local workspace and copying them back when the work is done.
In a text editor with a powerful MacroLanguage, this is usually written as some kind of custom buffer with code interfacing to the OS in order to access curl, FTP, SCP, WebDAV?, RSH, or some other kind of file transfer system.
In fact, this might make a nice article for somebody to write...
CategoryFeature?