Use a fondue pot, double boiler, or medium saucepan to heat the white wine until simmering.
Add shredded cheeses to a bowl and toss with flour.
Add minced garlic to the simmering pot. Add cheese a handful at a time into the pot, stirring until melted between each addition.
Stir in salt. If the cheese isn't melting completely smoothly you can add a few drops of lemon juice (the acidity will help break up the cheese and allow it to melt).
Serve warm with cubed french bread, apples and carrots--this is where a fondue pot comes in handy but you could also use your slow-cooker to keep it warm while you eat.
Notes
If you can't or don't want to use dry white wine, you could try substituting white wine vinegar or rice wine vinegar, but you may want to dilute it a tiny bit with water.