I made a Y-cable that took the TX signal (sometimes marked "OUT") from
the GPS and put it onto the RX pin on a DB-9.

Here is how I wire my Y-cables:

	db9		     
	computer             gps                radio           battery

	2 RX --------------- DATA-OUT --------- DATA-IN
	3 TX - NC.           DATA-IN  --------- DATA-OUT
	5 GND -------------- GND -------------- GND ----------- GND (neg)
			     POWER ------------ POWER --------- +12v

	1 CD ------+
	4 DTR------+
	6 DSR------+

	7 RTS --------+
	8 CTS --------+

	9 RI - NC  (No Connection) 

	db-9 pinout

	1 2 3 4 5
	o o o o o
	 o o o o
	 6 7 8 9

The 1,4,6 and 7,8 connections might not be needed with some software
and/or hardware that ignores the modem-control lines.  I like to keep
things general purpose so I always connect those.