Well, get some frogs like you are already doing, put them individually into a tiny bit of water and freeze them individually in it to keep them nice and fresh. Wash the rodent scent off the pinkie very well in plain water or even add just a bit of Ivory "un-scented" soap to do this. Then generously rub the frog all over the pinky(especially the face) to entice a feeding response from the Candoia when you offer it to the snake on a long thin pair of tongs head-first. You can do this many times with frozen items. Then simply gradually cut back on the amount of frog you scent them with over time. You can even stick a small piece of frog toe. or any small piece of limb that will fit into the pinkies mouth.
I would go over to the "Candoia (Ground Boa) forum" and ask those guys too. They deal with lots of reluctant feeders when they produce youngsters.
Anyway, when you scent prey items well, it usually works just as good as the actual prey item would. Heck, the snakes only care about what it smells like anyway..LOL! I do this alot with king and corn hatchlings with lizard scenting, etc...
good luck!
~Doug
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"a snake in the grass is a GOOD thing" 
my website -Serpentine Specialties