After you register I think they want you to send them an e-mail, at least that is what last years brochure said,
Last Years Botcon Brochure
Hasbro Designers’ Art Contests
Over $1,000 worth of prizes will be awarded! Each art contest will be judged by Hasbro designers and the winners will receive show dollars that they can spend with any dealer at the show. If you are planning to bring a display or contest
entry, please contact us prior to June 1, to ensure that we have space allocated. All entries must be in place for judging by 5 pm on Friday.
The June 1st was for last year so whenever Botcon will let us sign I'm sure that they will give us a new date for the entries submissions
Hope this helps you