My neice came to stay with us twice and had lice, then a friend moved in w/ us for a while and her daughters kept getting lice at school (we homeschool) - so we went through this alot!
Get a 16 oz (ish) spray bottle and fill it w/ rubbing alcohol - then add about 2 teaspoons of tea tree oil. (commonly reffered to as meluca oil) -- you can buy it at whole foods or sprouts - BUT you can also get it at Walmart -- it's in the first aid section, usually at the bottom of the shelf - dark brown bottle w/ tan wrapper and "TEA TREE OIL" in Dark brown letters - it is MUCH cheaper at Walmart than anywhere else.
Treat the hair just as you would w/ a conventional product. Start at teh bottom (nape of neck) and separate the hair getting every strand wet and making sure to pull off the nits and lice as you come across them, make sure to use a tissue to wipe them on so that when you are done you can flush it down the toilet (or put in a sealed ziploc bag in the trash). Repeat this 7 days later, and then 7 days after that so that you are sure you have gotten them all.
It's a pain - but the best thing is to go through the hair every single day and pull out anythign you missed!
Shampoos w/ tea tree oil or even coconut oil are good at repelling lice. When you send your kids to school, use hairspray or gel in their hair, so "neighboring" lice can't latch on to their hair.
Good luck to you!