The offset in "MarchCard.m" is for creating a visualization. We combine the image of the card and the image of me holding the card. Then we project the feature points found in the card image into the combined image, so that we can draw the lines properly. HTH!
Every deck of cards has a slightly different pattern to the face cards. ReplaceCard only works with the deck of cards from MathWorks, which we give away at events and tradeshows. But you can make it work with your object by replacing the reference image with one of your choice. The reference image is "MWqueen_crop_small.bmp".
Hope this helps!