Not having an XL-S not sure if this will work or not but here goes.
when you have your route made with google maps you need to zoom in both start and finish points and move them a few yards (you can move them back if you like)
Then open link tab and copy link.
Follow up : I beleave with the newer verson of Houghi you may not have to move start and finish locations.
Then go to this program and past link into blank box.
http://www.houghi.org/tomtom/
Then click on submit Query.
This will create a TomTom Itn file.
You can then save this file to a folder on your computer for future use if you like or copy it direct to your unit's itn folder.
( you will need to have your unit connected to computer for this )
Then once you have it in your itn folder all you need to do is go to ininery planning/options/ load itinery. chose the itn file you want and it will load.
What I do after it is loaded I view the the route, if it is long I browse as Image if it is short I click on demo.
(If you have IQ routing on you might want to disable it ? )
There is another free download program you can use with your TT as well if you like .
called Tyre.
http://www.janboersma.nl/gett/index.php