Could you please tell me more about this? Thank you for your time!
GSAK is available at
GSAK (Geocaching Swiss Army Knife)
I'm not sure what aspect of its use you're asking about, so I'll cover the basic one.
As a premium member at geocaching.com, you can create "Pocket Queries" to pull down as many as 1000 geocaches per file, up to 5 such queries per day.
Using GSAK, you can load all of the Pocket Queries into a single database and export them as a TomTom *.ov2 file, and slide that file over into your TomTom's map folder. Your TomTom will use whatever name you used to save the file (whatever.ov2) to display a new POI category for you in the same way it does all other POI categories. You can now navigate directly to a geocache (or as close as your vehicle will get you, anyway) and you can build itineraries with your TomTom (or Home) if you want to do a longer caching run.
If you create a little 22x22 icon called whatever.bmp and slide it over with the *.ov2 file (root name has to match), that icon will be associated with your POI when you view them on the map and in the POI list.
I go a little further and build 4 different *.ov2 files using GSAK. GSAK allows you to do some filtering (slicing and dicing of the database). I export one TomTom *.ov2 file of caches I haven't found, another *.ov2 file of the caches I have found, another *.ov2 of the caches I've found but are archived, and lastly, one *.ov2 file of my own placed caches. I call these geocaches.ov2, geofound.ov2, geofoundarchived.ov2 and geomine.ov2. The geofound.ov2 and geofoundarchived.ov2 come from a download of my finds (you're only allowed to download that once a week).
I'll attach the 4 little icons for these if you want to play with them, but you can create your own using Microsoft Paint or just about anything else that will generate a *.bmp file.