It isn't possible yet, but it is on the developers' "to do" list to add such a capability.
Your best course for promoting this, for getting card handling up to the top of the developers' list of priorities, would be to visit this thread: <a href="http://community.roll20.net/discussion/comment/4675#Comment_4675" rel="nofollow">http://community.roll20.net/discussion/comment/4675#Comment_4675</a> , and either to add a comment or to vote up some of the comments you most agree with.