Actually the haxxor bean is for members of the UBB team for fighting cancer. More info here.
As far as this box goes that you are trying to work with, you'd probably want to use an IF statement to check either group membership (all people who get rewards can be added to a group, for example), or check against another variable somewhere, perhaps in your database, that you could add. Then it would only show up for members who you set it up for.
I'd probably add a new field to the database to store the information and add an option to your edit users admin function to add/change the users reward image.
I can't help out too much right now, as I'm at work and have no access to my server files to give further examples. Perhaps someone else can kick in some info for ya.