After many and many, many, ... tests, I finally got a working configuration for my MultiFunction Samsung Printer (SCX 3405W) with "Scan to PC" button.
This button allow a direct scan to a configured computer (Mac or Windows, even if the config in Windows is really simple and automatic) from your printer: you can remain on your printer (scanner), change as many document as you want, and go back to your computer just in the end with all documents saved in the desired format.
First of all you need to install "Samsung Easy Printer Manager" software on your Mac, start it, and go to Advanced Mode.
If you can't reach this window (program crash when you click on the button) like me at the beginning, you should remove it using the Uninstall.sh script included in the downloaded ZIP.
Type, in a terminal:
Here you a have to select a folder where you want to put the scanned documents. But, in any manual I found information that images are sent using the samba protocol. This means you should allow sharing on that folder in read/write mode!!
[gallery link="file" columns="4"]