When I have to feed pills, I smash them up and, depending on which horse, add some water or a 50-50 mix of water and 100% pure apple juice. That way they can't blow the powder out.
You could also make a mix of the smashed pills water and cinnamon, since cinnamon is recommended for metabolic horses anyway
As far as a treat, Standlees straight timothy pellets make excellent treats for metabolic horses, plus they save the hassle of having to make treats. Standlee Hay Company - View Product
Tractor Supply sells Standlees products. The straight
timothy pellets come in a nuclear lime green & white bag. They make several blends so you have to read the bag and be sure of which one you're buying