As manager and director of football at Edu's club, Toronto FC, Johnston has been able to track the progress of the California-born youngster since he made his Major League Soccer debut in April 2007.
The move follows the capture of Portsmouth's Pedro Mendes yesterday on a three-year deal worth £3million.
Gers boss Walter Smith said: "We are interested in the American boy and we are trying to get him. But that depends on a work permit, so it will be a few days before we know about that.
"We had asked Maurice if he thought there were any players in the American league whom he thought would do well, and he recommended two or three players.
"The clubs don't own the players over there so the MLS are happy to let him go. We are in the final stages of tying everything up, but we still have to apply for the work permit.
"He is only 22 and has played the last number of internationals, so I'd hope we will get him all right. And he's played in the Olympics."