The best way to insert threaded inserts into wood is not by following the directions on the packaging. If you have a drill press available, this process will give you guaranteed straight inserts every time.

Use a threaded rod or bolt with the head cut off that has the same threads as your insert. Attach your insert to the threaded rod and lock it in place with a nut. After you drill the pilot hole for your threaded insert, chuck it in your drill press. Apply light pressure on the drill press while rotating the chuck by hand. The exterior threads of the insert will grab hold in your wood. Continue to rotate until the insert is flush with the wood surface. Loosen the nut and rotate the chuck until the threaded rod is removed.