Yes, actually that is a good idea. Not only will that help a little bit for excessive sweat regulation, but it will also help with excessive body odor (bromhidrosis).
Adding baking soda, corn starch, or a mixture of the two, in addition to whatever antiperspirant or deodorant that you currently use, should help you.
Some people actually create a 1/2 baking soda, 1/2 corn starch mixture, add water, and apply to their underarms in place of deodorant and antiperspirant.
Another idea that I've been hearing good things about is this 'Salt Crystal Antiperspirant'. Do a Google on that and see what you come up with.
Chris Mechanic
www.Bye-Bye-Excessive-Armpit-Sweat.com