If you can't figure that out you'll never finish. It's all about problem solving!
I had the same issue last year. I had to save it as a .xml, open it in Mapsource (Garmin software), save it in Mapsource as a .gpx, and then put it on my GPS with Topofusion (my favorite software) after reducing it to 500 points. It says it's a .gpx on the website, but I can only save it as a .xml file from the website.
+1 on problem solving!
On windows, right click the link, select save as..., all files, and name with a .gpx extension. Most browsers simply dump the xml to the screen if you click the link.
The PN60 has big track memory, so the OP should be able to use the 10,000 pt track for this. The higher res track will be nice for those times when its dark, raining, and you just aren't sure where to trail picks up again after a detour (like where is that darn trail at the top of Molas??)