For the 6x100mm bolt, i used phillips screwdriver that fit perfectly. It's just to hold the balancer gear in place while you put the pulley on (or when you install the balancer gear case on the oil pump casing)
As for your original question, the part you looking for is the little arm with a groove in the middle, right next to the spring on this picture (on the timing belt tensionner)
If i remember correctly, you adjust your timing belt tension, lock it with the cover bolt, install the balancer shaft belt, adjust, tighten adjuster bolt, then remove the cover bolt. Dont take my word for it, i havent done it in 3 years lol. But the cover bolt goes there.
As for your original question, the part you looking for is the little arm with a groove in the middle, right next to the spring on this picture (on the timing belt tensionner)
If i remember correctly, you adjust your timing belt tension, lock it with the cover bolt, install the balancer shaft belt, adjust, tighten adjuster bolt, then remove the cover bolt. Dont take my word for it, i havent done it in 3 years lol. But the cover bolt goes there.