Near as I know, it is not difficult to do, though you must receive and log ground and flight training from an authorized instructor on NVG use and receive a logbook endorsement prior to operating an aircraft as PIC using NVG equipment.
(k)Additional training required for night vision goggle operations.
(1) Except as provided under paragraph (k)(3) of this section, a
person may act as pilot in command of an aircraft using night vision
goggles only if that person receives and logs ground training from an
authorized instructor and obtains a logbook or training record
endorsement from an authorized instructor who certifies the person
completed the ground training. The ground training must include the
following subjects:
(i) Applicable portions of this chapter that relate to night vision
goggle limitations and flight operations;
(ii) Aeromedical factors related to the use of night vision goggles,
including how to protect night vision, how the eyes adapt to night,
self-imposed stresses that affect night vision, effects of lighting on
night vision, cues used to estimate distance and depth perception at
night, and visual illusions;
(iii) Normal, abnormal, and emergency operations of night vision
goggle equipment;
(iv) Night vision goggle performance and scene interpretation; and
(v) Night vision goggle operation flight planning, including night
terrain interpretation and factors affecting terrain interpretation.
(2) Except as provided under paragraph (k)(3) of this section, a
person may act as pilot in command of an aircraft using night vision
goggles only if that person receives and logs flight training from an
authorized instructor and obtains a logbook or training record
endorsement from an authorized instructor who found the person
proficient in the use of night vision goggles. The flight training
must include the following tasks:
(i) Preflight and use of internal and external aircraft lighting
systems for night vision goggle operations;
(ii) Preflight preparation of night vision goggles for night vision
goggle operations;
(iii) Proper piloting techniques when using night vision goggles
during the takeoff, climb, enroute, descent, and landing phases of
flight; and
(iv) Normal, abnormal, and emergency flight operations using night
vision goggles.
(3) The requirements under paragraphs (k)(1) and (2) of this section
do not apply if a person can document satisfactory completion of any
of the following pilot proficiency checks using night vision goggles
in an aircraft:
(i) A pilot proficiency check on night vision goggle operations
conducted by the U.S. Armed Forces.
(ii) A pilot proficiency check on night vision goggle operations under
part 135 of this chapter conducted by an Examiner or Check Airman.
(iii) A pilot proficiency check on night vision goggle operations
conducted by a night vision goggle manufacturer or authorized
instructor, when the pilot -
(A) Is employed by a Federal, State, county, or municipal law
enforcement agency; and
(B) Has logged at least 20 hours as pilot in command in night vision
goggle operations.