Jetfour,
As you don't have a socket for an external antenna, you might like to consider a GPS re-radiator. This device receives the GPS signals, amplifies them and then reradiates them through a little antenna that you can locate close to the GPS device. The GPS then receives the signal through it's internal antenna as normal.
Due to my car windshield being GPS proof
I bought the RRAD-45 at the following link and it works brilliantly.
GPS Warehouse: Smart Antennas
Hope this helps...
m.