I think the vast majority of folks come through MCO for cruises out of Port Canaveral, so it's a rather limited few who would have experience with MLB. If I were you, I would contact any of the private transfer companies who get recommended here, ask if they'll do a PC->MLB transfer. At worst they say "sorry, we don't go there" and at best you may find a great deal. You might also check the Transportation Forum to see if anyone there is familiar with travel through Melbourne.
Enjoy your cruise!