Carter recently left MWR to become the crew chief for Jamie McMurray at Roush Racing.
"Frankie has been running our testing and Reutimann has been our test driver because everybody else has been busy," Waltrip said. "They've had some wonderful tests and have worked real well together."
An official announcement is expected over the next few days.
Kerr, a former car chief for Robby Gordon and crew chief for Travis Kvapil in the Busch Series, will join Matt Borland (Dale Jarrett) and David Hyder (Waltrip) as crew chiefs for MWR's three Nextel Cup teams.
Kerr is a four-time champion in sprint cars with more than 200 wins in the World of Outlaws, USAC and All-Star Series that includes the USAC Non-Wing World Championship in 1998.
"If you know anything about modified racing on the East Coast, he's a legend," Waltrip said of Kerr. "He's another guy on our team that is a winner."
Jarrett will debut MWR's new Toyota Camry in the first preseason test session at Daytona International Speedway on Monday. Waltrip and Reutimann will participate in the next test on Jan. 15-17.
David Newton covers NASCAR for ESPN.com. He can be reached at firstname.lastname@example.org.