From the CCGHQ archives at https://www.slightlymagic.net/forum/
Here are some videos on how to scan cards and how to process them. These are from the Pre-AI era and Photoshop is involved.
There are some old file formats here so you'll need a decent video player like VLC.
Videos in this torrent:
How to Scan Magic Cards Dust-Free by Skibulk.flv
Cutting and Bordering Regular Cards by extreme.MOV
Processing Planeswalkers 1 by extreme.MOV
Processing Planeswalkers 2- example by extreme.MOV