Create a directory for your deck named anything

Download images of cards you want to use and name them w01, w02, . . . , w10, and b01, b02, . . . , b40. Remember, there are exactly 40 cards in a Main (Black) Deck, and up to 10 cards in a LRIG (White) deck. If you're running duplicate cards, just copy and paste and give them different names until you have 10 images for your White cards, and 40 images for your Black cards.
(Use the best resolution images you can, they will be scaled down appropriately)

Download and install http://www.imagemagick.org/script/binary-releases.php#windows (First is fine)
Make sure to leave 'add to system path' ticked during installation.
(If you're suspicious, this is a useful image processing utility to have)

Download https://www.mediafire.com/?8n6ghj59144saom and place it in the same directory as your cards

Run _createdecks.bat . You will have a _white.png and _black.png image for each respective deck
(If windows warns you, click more info and 'Run anyway'. If suspicious right-click edit the file to check the two commands it runs)