I'm trying to do the same thing and i found this.
"active antennas amplify the signal to get past the loss in the extra wiring; with a little bit of hacking, you can add an external active gps antenna to just about any GPS unit. Find out how in today's How-To."
http://www.engadget.com/2006/03/28/h...l-gps-antenna/
Anyone ever try this or find another solution?