1) Empty your enclosure.
2) Sanitize everything with hot water and bleach/dish soap.
3) Soak your snake for 20 minutes in warm water with a few drops of dish soap.
4) Put your enclosure back together: use paper towel substrate and keep the set up very minimal (only hide and water dish)
5) Put your snake back.
6) Get Provent-a-Mite (PAM) or Nix Lice spray to treat.
7) Repeat steps 1-5 daily until you can get the PAM or Nix.
Everyone's go-to treatment of choice is PAM (prevent-a-mite) and it does work, but another very good choice and actually a safer option is Reptile Spray from Reptile Basics. You would use it the same way as PAM except that you do not have to wait to put you snake back in it's enclosure and you can use the spray directly on your snake. This works immediately and prevents reinfestation too by killing the eggs. Just thought I'd throw that out there as another option for you. Mites are pain in the butt, but not the end of the world. Treat all your snakes though - mites can and do travel!