- get this file Download from http://support.apple.com/kb/DL905
- install it (of course)
- goto add printer dialog
- spot your printer, mine is on my airport extreme's USB port, it appears in the list of choices.
- it won't find the driver for it, that's normal, open "Choose a driver..." then "Select software..."
- look for "Samsung ML-1640" and select that.
- hit the "ok's"
- pat yourself on the back.
I am not promising you will never get any issues with this, but the solution has worked without a hitch for months on my setup.
You can try different printer models too for your different printer too. When it doesn't work, nothing should explode or anything.