The item he chose was a shirt he had worn when he was 12. He moved the baby to his bed, put the medallion around the baby's neck and touched it to the shirt until the baby begin to transform. But the result wasn't Scott at age 12; the result was a 12 year old who had his thumb in his mouth, cried a lot, and acted like a baby.
But an hour later, the 12 year old was walking around, if a bit unsteadily. Just like other transformed people could walk in a new body, so could baby Scott--even if he couldn't walk before. Another hour later, he was saying his first words, calling Scott "Mommy," despite his male form. It seemed that the longer the medallion was left on, the more the one wearing it knew how to use their new body. But after a day or so it stopped. The child had no memories, but Scott and his family figured that he was acting about like Scott did at age 8. Clearly the baby only got some of the mind of the clothes owner. And he probably only got that much because he started with a blank mind.
So Scott took another shirt--his, worn at age 8--and used the medallion again to make the child really be that age. At least he wouldn't be changing any diapers, though being a male mother to himself as a child was downright weird.
But the weirdness wouldn't get worse. Well, until two weeks later when Scott had left the medallion unattended, and 8-year-old Scott got ahold of it....
