The importation wizard will be available in the Settings > Technical menu.

An admin user can select the target model and field of the importation, and
select a Char field where to store the file name of the Binary being downloaded.

He can then list record IDs (either using Database ID or XML ID) and the URL
of the file to download and write into these records.

To create new records, a standard import can be made without the binary field first,
then a CSV like list can be copy pasted into the wizard to allow mass importation
without having to upload or list URLs one by one.
