Well, yes, but the idea was to avoid opening it in case I came up with a palm3.

You won't be doing anything that will damage your ability to hook it up to a palm3. If you do a nice job of making a clean hole for the serial cable, you'll have a nice StreetFinder with a dangling serial cable that can connect to either a Palm or the Empeg, whichever you like.

But I have to say that GPSapp is already better than any of the Palm software I tried, so there's no point in bothering with it.