Here is a sample deck. The sample deck is 1024x1024 pixels, with each packed card represented as 110x146 pixels.
1. Load the image to your photo library by opening the image in safari, then holding your finger on the image until "save image" is presented.
2. Open the iDevice Photo Library to confirm that the image is present and selectable.
3. Open Card Shark, go to "Options" then select the "Custom Deck" option. Choose the deck you saved in step(1).
Once a custom deck is imported into Card Shark, it will be used by Card Shark until you select an alternate deck. You don't have to keep the image in your photo library.