To expand on what AirBreather said, the new justices would have an 18 year term, replacing one every two years.
this is actually a reasonable solution I pushed a while back. Basically, it would keep the aspect of the court changing slowly (an intentional feature,) but it would still let it change. Further, each president gets two SCOTUS peeps at predictable times, removing the ability of the senate to play games and game the system. (or installing relatively young judges who will serve for forty+ years.)