How can I cool an under the counter icemaker?
I would 'push' and 'pull' with "muffin fans"  

I would locate the 'push' side in the toe-kick area in the cabinet to the left and put the 'pull fan inside the top left wall (in the cabinet to the right of the icemaker)  this should pull out the hot air at the top and supplement with relatively cooler air near the floor.  Fan shrouding, plug in timer for night time operation (muffin fans are loud) and safe electrical wiring are left to the reader to implement properly.