When I was a kid, my brother suffered from frequent ear infections, and our ped told my mom to clean his ears periodically with peroxide. I don't know how effective it is, but your ears do feel wonderfully clean once you're done.
Have your child lie on his side, with a tissue in his hand to clean up drops. Put some peroxide into an eye dropper and drop it into his ear. Warn him ahead of time that it will feel cold, but won't hurt. Once all the bubbling has stopped, which can take about 5 minutes, have him roll over and let the peroxide drain out into the tissue. Repeat with other ear.