You can try cup feeding like this:
Get a tall opaque cup plastic cup, or a small waste paper basket. Change the location of it daily. Your cham will still hunt. He doesn't know where the cup will be, and if it is large enough (like a waste can or plastic tub) he can go in (make sure there are branches that go in that he can get to but crix can't - about 4" from the bottom, or put shishkabob skewers in as a ladder). This will keep him moving and hunting, but will keep the crix from wandering around and hiding from him (I found that they would hide out in the planters). Also, crix can eat poop and things before your cham gets to them... not good. Also, you can make sure what your cham is eating. If he isn't for some reason, you will know right away.
Once Orion got to be about 6 months I started using a plastic cup and cup feeding her by hand. I'd hold it at varying distances from her, and made her work hard for some, and let her get others more easily. Good exercise for the tounge, and for her as well.
Also, when free-roaming to feed the dust can come off of the crix easily. Free-roaming can be done, but it involves a lot of thought... I like the hand cup feeding method best. But, for babies, tub feeding in the cage (like mentioned above) works really well.