The way to get the available CO2 out of baking soda is to put it in a nonreactive tray, such as a glass lasagne pan.
Take a plastic soda bottle and put a TINY pinhole in it so that when filled with water, it BARELY drips out- a slow, controlled drip.
Empty a box of baking soda into the glass pan.
Fill the soda bottle with white vinegar and hang it over the pan.
It should slowly drip onto the baking soda, providing the acid catalyst necessary to release the CO2.
It's not ideal though. CO2 boosting is really only useful when you have provided all your plants' other needs.