As far as live foods, I wouldn't use mealworms. Terrible choice; not very nutritious, hard to digest. Good live feeders for musk turtles include: ghost shrimp, small snails (don't go for trap-door style snails, especially for small turtles), and guppies or mollies. Musk turtles are pretty good fishers.
Mine won't eat anything but the pellets. I have a tank full of Molly's swimming around with them and they don't even think twice about them. Not even the baby Molly's.