Interarchy File Converters
File Converters are set like any other preference, and just like any preference in Interarchy, it can be set (using AppleScript or /usr/bin/defaults) on a per protocol, server, user and path basis. So for example, you can set Interarchy to use the gzip file converter on everything in your /path/compressed/ folder on your SFTP site like this…
One of the built-in converters is for Interarchy Backup Format, a souped-up AppleSingle that tries to preserve everything.