You could use an intermediary program like QGIS that reads KMZ, then export to a format that is SU-friendly. QGIS is open source and free.
See below for process.
Step 1. Draw your Path in GE. Then ‘Save as’ KMZ.
Step 2. Open your KMZ in QGIS. Then export to DXF format. No need to do anything else in QGIS. If someone else knows a better way to convert KMZs please do tell.
Step 3. Import the DXF into a Geo-Located SU model. Unfortunately you lose the real-world positioning of the path when going changing to DXF. There’s always some trade offs. But just realign manually or using reference snapshot from original GE map.
Step 4. Use SU’s Sandbox tools to ‘Drape’ the boundary over terrain layer if so desired. That’s it. 10 mins of work. Not too bad once you’ve installed QGIS.
Or you can try this method from older post: How to import the attached kmz into SketchUp? - #2 by Geo. Haven’t tried it but seems a but labor intensive and may or may not give exact result you’re looking for.