If you are adding the peat pellets into a HOB type filter you could use the toe off a pair of panty hose, simply tie off the end place inside your media basket.
Peat plates used to be available to run under the substrate, not sure if they are still available though.
You could also make a blackwater extract, or buy one that you would add after doing a w/c. Usually 1 or 2 drops per gallon.
You could just use regular 'ol peat as well, but kinda messy to work with indoors
Edit: What TIMWAG mentioned above about making the extract works very well in my experiences
"an ounce of prevention is better than a pound of cure"