i'm doing a buttercream wedding cake and they want a ribbon border, can you do that? will the crisco soak through the ribbon and discolor it at all? what should I do?

you can use real ribbon on buttercream. If you're making the cake the night before, go ahead and put the ribbon on, the crisco will stain the ribbon, but it will stain all of the ribbon uniformly, so you won't be able to tell that they're grease stains, rather that the ribbon was like that. Make sure that all of the ribbon is touching the cake.

You could cut a piece of wax paper the same width as the ribbon and put it around the cake and then wrap the ribbon around the wax paper.

Have you tried using a non-toxic kiddies GLUE STICK? Rub the length of the ribbon and attach to cake. Keeps it in place the entire length, and forms a barrier....