I've made a new (better) open-source overclocker, it supports different core and memory speed combinations.
My dingoo reliably clocks to 448MHz core clock with 149MHz memory clock as I suspect most will with this new overclocker since it sets all the internal clocks better than A600's app. TV-out still doesn't work while overclocking.
This overclocker comes with a simple to use graphical user interface too, and dumps information about the internal clocks of your dingo, aswell as telling you the current clock speeds.
The overclocking code in this application has been added to the dingoo native sdk so that it can be integrated into other applications with relative ease, one downside seems to be that the OS randomly resets the clocks when certain applications start so it may only work for certain apps/emulators.
You can download it from google-code here
or a mirror here