Since the software supports that one piece of firmware it should just come wiht it. No codes, no hassle. If it can't just come wiht it, then it should just be downloadable by all since it would only work wiht the Wii mote to begin with.
Eurogamer is reporting that Nintendo is clearing up confusion about the ability to resell "Wii Speak". From the article:
"Any consumer who may have misplaced their Wii Download Ticket number for the Wii Speak Channel or require a new number following a Wii exchange may contact their local Nintendo Customer Services department, where they can request a replacement Wii Download Ticket number."