First Licker in Leon 2nd Scenario is unavoidable, when you walk under it he will always drop down and attack you.
That, or he really really hates me.
Anyway, since your strongest weapon at that time of the game is the gun... i discovered that a flash grenade works.
While he is stunned, run like the wind because else he will maim you.
Trust me, before thinking about the grenade i tryed many many times to simply run under him.
No matter how fast you could be, he always catches up and he will slice your back.