From MEPIS Documentation Wiki
Install garmin-forerunner-tools from the repos for CLI synching.
Nuvi 660NA and 1300 are reported to work with the USB cable, and mount in Device Notifier as soon as it is plugged in.
The MEPIS 11 package qlandkartegt-garmin contains a collection of plugins for QLandkarteGT to talk to various Garmin GPS devices, including GPSMap60CSx, GPSMap76, eTrexH, eTrexLegend and similar GPSr; it is available from the repos.
Plug in the unit, wait a few seconds, then open a terminal and type
dmesg | tail
and note the vendor and product IDs of the Garmin unit (two 4-digit numbers separated by a colon). You can get more information by doing an internet search on those numbers and the word "Linux").
Open Synaptic and type "garmin" into the search box to see what is currently available.
Tips and tricks
You may have to fix the unit's permissions to gain access; consult the OpenStreetMap link below.