Picture 1. Create 8 new polygons according to the picture.
Create 8 new polygons to the back of the ear according to picture 1. The idea is to decrease the amount of polygons so that it would be easier to attach the ear to the 3D-model of the head.
Now the geometry of the ear is complete. At this stage you should finalize the ear as much as possible.
Picture 2. Create a spline object out of the selected edges.
Picture 3. There is a hole in the place of the ear in the head model.
Now the ear is complete and next you will attach it to the 3D model of the head. Activate the border sub-object mode and select all the edges surrounding the hole according to picture 2. After that click Editable Poly's "Create Shape From Selection" button. Choose Linear as a Shape Type and click OK. You just created a new spline object. Hide the ear and unhide the head. The situation should now be similar to picture 3.
Picture 4. Create 13 new polygons according to the picture.
Activate vertex sub-object mode and use Editable Poly's Attach button to attach the spline object to the head. Spline object will disappear and its vertices are now part of the 3D-model of the head. Activate polygon sub-object mode and use Editable Poly's Create function to create 13 new polygons according to the picture 4. Now there is a hole in the head which matches exactly to the hole in the ear.
Unhide the ear and attach it to the head by using Editable Poly's Attach function. Now the head and the ear are the same object but there are duplicate vertices in the seam which must be welded. Select all the vertices (24) in the seam and click Editable Poly's settings button next to the Weld button. Rise the Weld threshold value big enough so that the amount in After is 12 less than the amount in Before. Click OK.
Move vertices in the ear and around it to make the ear look as natural as possible. Also fix other parts of the head if necessary.
Page 10: Finalizing the Head in 3DS MAX