The A520's a great camera, so I can understand why you'd want to get CHDK running on it.
From what I understand (I sat on the sidelines of Canon hacking until CHDK), a lot of talented people were working on hacking DIGIC cameras for quite some time, but the only big successes that I know about were: the hacked firmware for the EOS 300D (aka Digital Rebel) and some small firmware patches for compact canons that removed the 30 second limits on 640x480 video. AFAIK these were both primarily a case of unlocking features that were 'hidden' in the firmware. They were still amazing successes, but a lot more difficult to build upon than CHDK, where it's now extremely easy to add new features.
Because of the lack of a breakthrough success like CHDK, I don't think there are many centralised resources on hacking DIGIC. Try searching for 'undutchables EOS300D' (Undutchables is the name of one the most successful hacked firmwares for the EOS 300D).
I hope you will decide to exchange your A520 for a CHDK-compatible camera and put your enthusiasm to good use improving CHDK, but good luck in either case