You want to scrub it first with a detergent based cleaner to remove any debris. If there is a lot of stuck on poop, using a handheld clothes steamer will really help to loosen things up with the added benefit of killing any mite eggs found in the tiny cracks of wood.
Then you can follow up with a disinfectant--mix according to the bottle and pay strict attention to contact times. If you use a bleach solution, the dilution is 1:10 with a minimum of 10 minute contact time. You may have to rinse with plain water afterwards to prevent lingering fumes.
A really good non-toxic disinfectant is Oxine AH, but don't activate it with citric acid. As long as it is unactivated, you can actually hose down the bird with it without having ill effects (except a ****** off bird) as it degrades into ordinary table salt.
