I'm not to sure about the roks being in there? Anyone wanna add anything to that?

If I were you I would take EVERYTHING out.

Take 6 sheets of plain old white paper towels, fold them up all neatly so they fit into the bottom of the tank and WALAH! A substrate!

As for the worms, alive are always better... and if you have the paper towel substrate they will not be able to burrow so he can find them easier. Something that helped my Char eat was getting a food dish, putting a TINY bit of water in the bottom (so the worms don't dry up) cut one worm into 3 pieces or more and dropping them into the water. The more guts and blood sadly, the better :/

Next I think the snake would LOVE it if you had some foliage in there. Go to a dollar tree and buy some fake plants for him/her (S)he'll love you for it! OR if you don't want to spend the money go find some sticks in a forest or park! Heat up your oven to 220F and bake them to kill all the "things" that may be in/on them.

Also as for the cardboard box, it would be better for crickets... Try using a plastic bottle, glass jar, etc. Or even better is a piece of large PVC pipe cut in half .

And I said before about the small rocks and the substrate. Find a BIG rock. Not overly huge, just a nice sized big rock. Place it in there for him to climb on, lean some sticks up against it, I think that the bigger rocks give them a nice out-doors and natural habitat feel now that they are in a tank And it's a plus if he begins shedding and needs one!

Good luck I hoped I helped some :/