Could be wrong but I don't think something like that would be possible without some serious emulation type software on at least the PPC end ...
Maybe it would be an easier option to get a small external USB GPS reciever ... A quick Google Shopping search turned up this one ...
"Holux USB Mouse GPS Receiver GR-213 for PC (WAAS, USB Connector)"
This morning it's listed there for $39.95 ... It uses a USB or bluetooth connection. The bluetooth is nice because you can set the reciever up somewhere that it has a clearer view of the sky (and it's one less cable connected to your laptop) ... It charges off the USB port but its battery life is enough that you can just charge it for a few hours and it will run most of the day ...
I bought the same one a few years ago (before we had use of out Titan GPS reciever) and it works like a charm ...
In any event, excellent question, I hope you get a better answer.