Twister!
or
Three:
One to write the light bulb removal program,
one to write the light bulb insertion program, and
one to act as a light bulb administrator to make sure nobody else tries to change the light bulb at the same time.
or
Only one, but the bulb has got to really WANT to change.
or
Five: one to handle the bulb and four to contemplate how David Sanborn would've done it.
or