L -> 2 -> D

for auto~ but that's suicide~

what makes you think it will damage the engine n gearbox..
every gear is independent with different ratio.

Skipping gear from lower to higher wont do any damage.. provided ur engine has enuf torque to handle it.
Its different when downshifting.. too much speed for the gearbox to handle.. and tear and wear to the clutch if the engine speed is not syncro to the engine speed when the clutch is being release.

juz my 2 cents

Double clutching also wont help .. u need to sync the engine speed with the wheel speed to minimize the friction during downshift.

Autogear are not meant to ride that way ... will damage the torque convertor i guess.. not quite sure for auto thou.. but my fren use to do that all the time... his wira 1.5A.. end up .. during normal drive... if he put to 'D' .. the car will move with its 3rd gear... lolz.. it juz wont shift itself anymore...