If you could place a browse button to replace the "cardback.jpg", users could set a local instance of a card sleeve in their app.
Obviously it would take a code change to allow this idea to be unique to the user, but it would be nice for non-techie users.
If you decide to add the individual user card sleeve option, it would be great, and I could replace the original cardback image for the app on my system.
Trevor has said he might be bringing on another developer or two, and if so, Lackey could actually get updates again. Maybe even a feature like this, which I agree would be nice. Fingers crossed.