It would be as always - you post a photo as a prompt and let the writer know if you prefer gen or slash. Writers claim the photo anonymously and then write something to go with the photo. The stories can run from 100 word to however long you want. Stories will posted starting on the last weekend of October. You don't have to take a prompt in return, but it's more fun that way.
To get a bit more participation - stories can be any genre from MFU to NCIS to Doctor Who to The Addams Family to who knows what. To see some of the past offerings, drop in over at The Scrapbook and check out the offerings under the Halloween tags.
So, tell me what you think.