Rooney has made two youth international appearances and became Stoke's youngest ever hat-trick scorer in only his second match, during season 2005-06.
The Inverness manager strengthened his attacking options earlier in the summer by signing former Ross county striker Andy Barrowman, who scored on his debut in last week's win over Aberdeen.
Brewster hopes Rooney and Barrowman will be able to replicate the goalscoring threat carried by Marius Niculae, who left the club in the summer.
"We had Adam over in Denmark with us for the week and he was superb," said the Inverness manager.
"He got on great with the rest of the lads. He was excited about coming here and we were excited about him too."
Rooney and Barrowman will vie for a first-team place with other strikers Garry Wood and Rory McAllister.
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