You have not yet been requested for an Interview....only updated documents are required.
Since you admit to having a LONG interview at the Canadian Border at a Refugee board, all the details of that Interview is with Canada. I am sure they must have asked - Why do you seek Refugee status? My best guess answer - You must have told them the TRUTH that you overstayed in US. If not, then I can not continue with my post....because then it would be a "Shut case". I can not imagine what else you might have told them.
Now, if you told them the truth, then that has been documented. Canada has got ZERO tolerance for Criminal activity and for people who do not respect the LAWS. Even though you disobeyed the US laws, your file is under Stringent Scrutiny with top priority in CANADA.
Here's my suggestion: How long ago were you requested to provide the docs and how much time do you have? If you have more than 30 days, I would suggest you to order CAIPS to get a detailed insight of what the VO might have noted down the reasons for an Interview, if scheduled.
It has been a very long time since the incident....try to recall the Interview with refugee board and under no circumstance conceal any information - good or bad. You do not want yourself to be banned from Canada because of this.
Please do not be offended.....I am just trying to paint a realistic picture.
Mitali