I want to do a deep hack on my HP OfficeJet v40

[tenba]

Hi, I have an HP OfficeJet v40, and I want to hack into it so I can use its built-in optical sensor to detect the border on a pre-printed form so that I can determine what offset to print my content so that it lines up nicely inside of the boxes of the form. Has anyone else attempted something like this? I've done some embedded systems stuff before, but I'm hoping someone can offer some info so I don't have to take the whole thing apart and decompile the code byte by byte.