[celstu1]

Try this.... keep a baggy of some special kibble in your pocket all the time, whenever he gets something and you want to trade you have the baggie with you.

Another thing to try is feeding him in a bowl you can take away from him. When he's partly done eating, take the bowl away. Make him sit and give the bowl back to him... do this quickly though so he does not lose interest in his dinner. This basically teaches him to look to you for when it's time to eat. Teach him NO also. When I am prepping dinner and I drop something on the floor my boys can usually snatch it up in 2 seconds since they are always nearby. This worries me because of the toxic ingredients I may use, like onions. They both know that "NO! LEAVE IT" means back off and don't touch it.
When my boys were babies, I used to take away their treats, right out of their mouths. I used to feed them and take their food away mid-meal. I'd give it back in a few seconds and do this a couple times during a treat or meal time. I did this in the hopes that they could trust me to give them back the good stuff, and not get territorial or aggressive. It seems to have worked because now I can just say 'give it' and they drop whatever it is in my hand. My mom has a shih tzu that is aggressive with food or treats BIG time! I always tell my mom that someday she'll get something really BAD for her and she won't be able to get it away from her!