A room script. It sets the player’s gravity to zero when entered, and to normal gravity when exited. This is a copy of a script used in System Shock 2.
Create a negative-gravity room that lifts the player. Then at the point you want to stop, create another room with positive gravity and add this script to it. For best results, the room boundary should be at least 0.5-1.0 units above the floor that the player will walk out onto.