The left-hander, currently on the disabled list with a right hamstring strain, has not been activated but isn't too far off.
Red Sox catcher Jason Varitek, who is also on the DL recovering from a broken foot, served as Okajima's batterymate during the session.
"I asked [Varitek] how he's doing and he said he'd like to play tonight," Francona said. "That's not happening, but by his answer, it means he's doing really well. We'll wait and see how he's progressing the next couple of days. Obviously, he has to be cleared also before he goes on a rehab assignment. We don't know the timetable."
Meanwhile, fellow catcher Jarrod Saltalamacchia (leg infection) begins a minor league rehab assignment with Triple-A Pawtucket on Friday night. He will serve as the PawSox's designated hitter Friday and will catch on Saturday.
Sox utility man Eric Patterson (neck strain) will play second base for Pawtucket on Friday and serve as the DH on Saturday.
Joe McDonald covers the Red Sox for ESPNBoston.com.