iPaq H5550 and GPS Satnav help

[JayCee]

I bought this http://www.mobilefun.co.uk/product/8590.htm to use with my ipaq and I can connect and paired it.
I have MS Pocket Streets on my PocketPC which is essentially a PocketPC version of Autoroute with support for GPS.

I know the GPS unit is working okay as I also paired it with my Desktop PC which has a bluetooth dongle and I started Autoroute on the PC and got a fix on the GPS unit viewable on-screen within Autoroute.
When I paired the GPS with my Desktop it allowed me to pick the serial port to use (COM4).
When I paired it with my iPaq and connected I started Pocket Streets and under "Configure GPS receiver" it allows me a choice of 3 serial ports...

COM1,COM3,COM9

I have tried all 3 but it will not connect...how can I find which serial port the GPS wants to use...I was able to select COM4 with my Desktop?
Or, is there a setting in the ipaq where I can select a different serial port?
Within the iPaq if I go in to "Settings", "System", "Bluetooth" under "Serial Port" under "Ports" is

Inbound Com Port 5
Outbound Com Port 8

Can anyone tell me if these are fixed?...I thought I could bring up the soft keyboard and change them but it won't allow me.