This may not be the best place to post this but I'm not sure where else it would fit.
So I started to hack around with my MG5220 a bit.
I downloaded the service manual:
http://www.4shared.com/office/HEzwqoJT/canon_pixma-mg5220_sm.html
I found a 64-mbit ROM chip (MX23L6454), desoldered it and...