Of course there's supposed to be a tool for this job, but with a little ingenuity you can fake it. What you need to do is to hold the nutsert from turning, and tighten a bolt into it so that the back side is drawn up (It's just like a big pop rivet). One way to do this is to get a longish bolt that fits it, and put a nut on that bolt, and a washer, or a couple of washers, between the nut and the top of the nutsert. You now have the nutsert in the hole, with, in sequence, washer(s), nut, and bolt head. Now if you hold the bolt head from turning, and tighten the nut, it should pull up on the nutsert and expand it in its hole. You might have to put a little oil on the washers - they're there so that the nut will turn without trying to turn the nutsert itself. If the nutsert is a loose fit in its hole it can be very difficult to get started, but once it's begun to expand it becomes easier.
