Step 1: Open It Up
Now--be very cautions, the bulb in the scanner unit contains mercury vapors, and has the durability of a piece of uncooked spaghetti. Mercury vapors are invisible in most conditions.
Unscrew the brackets holding in the mirrors in the bottom of the unit.
Step 2: Assembly(A)
There are two thicker ones, and 1 thinner one
Align the mirrors as shown:
(or however you like, if you think you can find a better arrangement)
Step 3: Assembly(B)
Your more than welcome to hold it together any way you want.
In these pictures I blocked the end, this is just ambient light coming in the sides where I didn't tape.