This is one of the GPS watches that exports PWX files? If so, there are various sites on the web that will convert the PWX to a TCX file for you, and you can import that; also a program called sporttracks which can import your PWX file and export a TCX. Sporttracks is worth having anyway, very good for reviewing your data.
I've only ever tried one at a time, not sure if you can export more than one. How good are you with computers? I'm working on a Python program to convert pwx to tcx, not being entirely happy with other converters I've tried.