Can I put a little baking soda in my TT toilet?

Sure you can, but it likely won't help with the smell. Baking soda helps by adsorbing molecules from the air (as does activated charcoal, more effectively). Dump the soda in the toilet, it will just dissolve, no adsorption.

I put sodium borate and laundry detergent in mine, not so much for smell as to help dissolve stuff and keep it suspended.