Go to bevhoward dot com/G2WPT.htm (sorry, I can't post URLs because my post count is too low) and install the GMap2GPX shortcut/script to your browser's shortcut bar. Then, go the the map link you posted, and while on that page click the new GMap2GPX shortcut. This will open a browser page with XML data in a window, with different options for "full," "points" and "track." I use track as it gives all points throughout the entire route you've mapped.
Then, copy all the XML in the window and paste it into a text document (if you're on a PC you can use Notepad, TextEdit on a Mac). Save it as yourfilename.gpx and open it in Garmin MapSource (BaseCamp on a Mac). You should see the route. You can now export that to your GPS.
The only thing with Garmins is that some (like my 60CSx), limits track points to a maximum of 500. That means you either have to filter the points down (lower resolution/less exact) or cut that XML file up into multiple tracks, which is a bit more involved.
Give it a shot. It's easier than it sounds!