Sorry - trying to find recent Canon camera's supported by CHDK has always been a challenge. CHDK development is an all volunteer process and usually requires a skilled developer who has access to the camera and the desire to do a port of that camera. And that creates a lag in CHDK releases relative to what is actually available in your local camera store.
For reference, to help you understand the CHDK development process :
link> CHDK FAQ : My camera isn't ported yetYou can find a list of pretty much every Canon Powershot and its porting status here :
For DevelopersSorry that I don't have more specifics relative to the SX710SX. If there is any progress on the port for that camera, it will likely be posted here :
SX710
