How do you determine when a company is in this “too big to fail” category, to get access to this program?

If a company is about to go bankrupt and congress decides it's too important to let that happen, exactly how it happens currently

How do you draw the lines in that company to fractionate it? Geographically? Randomly?

That's for business people, lawyers, and politicians to figure out, it's happened multiple times before, look into the breakup of Standard Oil or Bell