Oh my!  Lice - ick!

Ok, now to eliminating the greasies.  I'd start by shampooing with a clarifying shampoo, followed by a vinegar rinse (about 1/4 cup vinegar added to a 2 liter bottle of water, poured over your head and hair.  Be sure to keep it out of your eyes.)  Use a light conditioner on the length of your hair, don't use it on your head.  Use cool or lukewarm water for your final rinse.

Hopefully this will help.  (and good luck with school next week!)