The most common ways are to enter a room in direct G-mode, back up into the open doorway, then exit G-mode to have the door close on Samus.
This can be used to initiate a 'deep stuck' X-Ray climb, which can enable Samus to climb past slopes which are in the column of tiles in front of the door shell.
This can also be used to initiate a 'very deep stuck' X-Ray climb, which can enable Samus to climb up and trigger the transition of a door above without needing to open the door.
Much less common examples include overloading PLMs and exiting G-mode while inside of overloaded blocks to solidify them and enable an X-Ray Climb; this variant will also require canComplexGMode.
See also: Tech Page