I don't know where to ask this so I'll start here... I have MS Streets & Trips with GPS and was wondering if I could somehow use that with a 396XT linked to my laptop... Can anyone help?
I am just in the process of doing sort of what you are thinking of. Trouble is that the cable on the MS GPS recvr is actually a Serial to USB converter ( or possibly more correct a TTL to USB converter) the TTL voltage levels that come out of the puck where the cord plugs in are too low to provide data to the scanner. Easy to fix with a TTL to Serial converter chip. (MAX 232 is one brand.) You need to power everything with 5 volts (The power from the scanner batteries is fine). You will need to be willing to split the plastic case open on the GPS and do a little soldering or sacrifice the cable to hook things up.
I am going for the opening things up option and making a single unit that will just slide on and off the back of the scanner using the belt clip to attach it to. There will be a connector on the back of the scanner, under the GPS attachment, so no wires will be external.
Will post up details when finished, maybe later this week when my TTL to Serial converter arrives.
Stay Tuned!
As far as somehow using the GPS hooked to your computer, then passing the data on to your scanner, I don't know how that might be possible.