Good luck, Chris, and let us know how it goes. Going by size, that suggests he's a teenager-ish crestie. I take it he's sexable and the 'he' isn't just for convenience or a guess. Crickets definitely aren't a sufficient diet for him at that age, so hopefully he will take the diet easily. You can also withhold crickets from him for a week or two as a means of persuading him to try other food. When he gets hungry, he'll eat.