I am a big YNAB fan, and it is very different from mint or yodlee. Mint and yodlee track, and give you historic info. YNAB requires more control and forethought, and you base spending decisions on it; it's not a look back. Believe me, I thought it was stupid when I first realized it required manual entry, but it is second nature to me now, and it has allowed me to control spending way more than anything else I've used before. I was a good saver before and YNAB is super charging my progress.
If he likes the idea of it, just have him report to you at the end of each day what was spent, and if it doesn't cause you to spend more, try to have him keep cash transactions down. You can look up electronic transactions in your online account activity and enter them. Actually, sometimes I use yodlee to check on transactions in case DH forgets something. If you are getting close in a category, let him know you are trying to get to x date with only x $ for groceries.
DH and I both "use" YNAB, but really I am the only one that touches the software. I reconcile our pocket cash, checking, and main CC balance about once a week, and check for transactions from DH periodically (either at the CC site or yodlee), and let him know if we are getting tight on anything. We have similar spending habits, though, so I don't need to worry about him going out and blowing $100 on shoes and ruining our budget plan for the month.