Yes, you can! You’ll receive your WOWPoints in full from the first deduction.
For example, you intend to buy a Classic 11 that retails for $89. If you pay using Atome (i.e 3 monthly installments) and use a $10 WOWReward, that means it’ll cost $79. Split across 3 monthly installments, this means you’ll only pay $26.40 per month.