Peguero would have to pass a physical before the deal becomes official.
"We're working on it, but nothing is in place," Duquette said. "It's not a done deal. We're still in the process."
Peguero, 25, went 6-for-29 with the Giants this year, posting a .207/.233/.345 line with a double, home run, four runs scored and two stolen bases in 18 games. He was 3-for-16 with seven strikeouts, six runs scored and three stolen bases in 2012.
Peguero is a career .306/.337/.427 hitter in eight minor league seasons, with 36 homers, 350 RBIs and 131 stolen bases. He batted .316/.354/.408 with three homers and 30 RBIs in 288 plate appearances with Triple-A Fresno this year.
"He can play all three outfield positions," Duquette said. "He's got a good arm and he's a .300-plus hitter in the minors."
Peguero was rated as the Giants' fifth-best prospect last year by Baseball America.
Adding Peguero to the 40-man roster would leave two vacancies with the Winter Meetings starting on Monday.
The Orioles remain in the market for an outfielder despite the pending addition of Peguero, who signed with the Giants as an amateur free agent in 2005.
Note: Outfielder Jason Pridie, non-tendered by the Orioles on Monday, has signed with the Rockies. He tweeted the news this afternoon.
"@MrPriddles I'm extremely excited to become a part of the @Rockies organization. Nothing beats living at home for Spring Training!"