Most chams will learn to shoot feeders out of a cup, but it isn't best for everything IMHO. Sometimes they can lose muscle tone in their tongues, have problems with eye-tongue coordination, and develop problems shooting at prey. Plus, it isn't very interesting for them and doesn't permit them to carry out a natural behavior. Tongue trouble is also a sign of nutritional problems.
I've always prefered to give my chams some choice...some feeders are better kept in a container so they don't escape or hide in the cage (where they can pick up fecal matter, molds, bacteria or lose their gutload too quickly). Other feeders can be offered by hand or released in the cage while the cham is active. Hunting feeders gives your cham something to do with brain, tongue, eyes, etc. After all, one of the reasons we like chams is the amazing stalk, aim, and shoot!
I like to offer feeders in a larger plastic box set in the cage. The feeders can move around more and attract the cham's attention, I can put fresh gutload in the box to keep them full, the cham can climb down to the rim of the box, and it has to stretch its tongue to reach them. Remove the box at night. You'll also have a much better idea how much the cham is eating. A cham who doesn't have to move around to find the food can sit hunched right at an empty bowl waiting. Pretty boring.