Does anyone know how I can use the GPS unit in my XDA Stellar with my N800 running OS2008?

Is this even possible?

See:

https://garage.maemo.org/projects/maemo-mapper/

run gps proxy in ur wm device and reroute to bt serial.

If your GPS receiver has a bluetooth interface, then all you have to do is pair it with your N800 and set it up as a GPS source in the Control Panel. See the "GPS location" settings in the "General" section of the Control Panel. Once you've paired it, you should be able to use it as a GPS source with either Maemo Mapper or OS2008's built-in mapping application.

How can we pair a typical Bluetooth GPS device with the N800 and make it the GPS source, when we have no display on Bluetooth device and no way to confirm the passcode code request provided by GPS Location settings applet running on N800?

Apologies if this is a stupid question.

Most gps devices have a "default" pin. The destructions that came with it or the web site should tell you this. My pharos is 12345678. You just put that pin in when you're setting up the device.

Thanks, that was enough information to jog my memory of the little paperwork that originally came with the BT GPS device, indicating in my case 0000 as the default pin.
(Did not have paperwork with me, but suddenly jumped out into my consciousness, entered it and it works; BT GPS Paired)

I never needed to Pair my BT GPS device for use with Maemo Mapper on my Nokia 770 & N800, but with the map application provided with OS 2008 Beta, I had to pair the device to make software see the GPS. (Interested for feature comparison purposes only, MM is my preferred app)