I have SFTP accounts base in Core FTP config.dat file. This server is not actually in Crush's IMPORT list.
I don't know if one of represented in the list servers like BulletProof, Wing, Serv-U etc, has the same format for stocking it's users.
Its not currently supported. If you do a CSV file, we can import that flexibly...
Otherwise email support@CrushFTP.com with a sample file for us to see if we can make an improper for core.