Yup.. pretty easy. Just did it for a Hotel Deposit on my Wife's Card. When the Transaction is posted to the card you just login to the tdrewards site then submit a request with the Transaction info and amount of points you want to redeem against it. Its 250Pts/$1 instead of the 200Pts/$1 using expediafortd but its painless. They have taken the points out now of my wife's balance but transaction credit should show up tomorrow or the next.
I only did it this way so my wife wouldn't have to call in. If you call in the rep's (Even the CC Reps) can do it for you was well and it's quick.
Scotia Rewards is the same. Once the transaction posts and you can see it in the scotia rewards site you can apply a credit the same way. Easy peasy.