I just found this on Jack Keller's website:
Another stabilizer is sodium benzoate, sold as a chemical or as Stabilizing Tablets. Its action is much the same as potassium sorbate. One crushed tablet per gallon of wine, added in conjunction with one crushed Campden tablet per gallon, is usually sufficient to stop fermentation. It can be added to the wine at the same time as sweetener and just before bottling, although I recommend allowing the wine to sit for several days after stabilizing to allow any dead or dying yeast to settle out as lees. It is less obnoxious, in my opinion, than potassium sorbate, but it does contain sodium. Use your own judgment.
Finally, a product called Wine Conditioner can be used for simultaneously stabilizing and sweetening a wine. Wine Conditioner is a mixture of potassium metabisulfite, potassium sorbate and non-fermentable sugar. It comes with instuctions.