Old dog

I have crossed over a number of dogs, and helped owners crossover their dogs. I like to start with targetting - target to hand or target stick.
I also like to use heeling - c/t (click and treat) for being at my left leg (use the 300 peck method, described elsewhere on this site)
Then I start them on object interaction. I simply c/t for any interaction and then shape whatever seems most easy .. put your head into the box, step into it, whatever the dogs likes to do... doesn't matter, the purpose after all is just learning to learn.
Of course choose very palatable treats. Something irresistable... might have to work with smelly cheese or freshly roast chicken the first few sessions...
keep the sessions short - stop while he still wants more.
Keep the ROR (rate of reinforcement) very high. Im one minute (60 seconds) you should be able to use at least 20 or 30 treats. If not, then lower your criteria. This is why I love to start out with hand targetting. You can get in a lot of nose-to-hand touches in very short time, and you can hold the hand realyl close to the dog if needed.
similarly with heeling - c/t for each step, and use directional changes to keep it interesting.
And keep those sessions short!
I would recommend that you read e.g. "clicking with dogs step by step in pictures". It's a great book for a clicker-beginner.
good luck
Christina