Silkworms are a great food addition. Start slow-maybe order 25-50. My Veiled took a week to finally eat one and the worms grow fast, I had to give a bunch of them away beause they got too big for him. You just place them on vines around the cage-they will find them eventually.
Every Cham is different. It may not accept a new food at first or it may go crazy as if it's never eaten before.
Every cham I've ever had has accepted all food items without reservation. I would start with Silkworms however. Chams love 'em. For my 2 chams, the first food I offered both of them were silkworms. Immediately after the most stressful time of their lives (being shipped from Cali to Michigan), I offered silkworms several hours after they were introduced into their cage and they ate the worms within minutes.