Originally Posted by CAAD5AL

The hook is there for when you're removing a tire, to lock the end of one tire lever onto a spoke so it stays in place while you work the other around, but if it works that way for installing a tire too, go with it!

Either way, be sure your using the lever to kind of slide along the rim vertically so you're sort of slowly sliding the bead up and on (or off) rather than trying to "snap" it into place.