MapSource Forum

Yeah!

First a note, almost all install files I now use through sshfs, which proves to be a very reliable way to access CD's, DVD's, unzipped folders or whatever

$ sshfs localhost:/your/path/to/install_media /mnt

And then choose /mnt as source folder for your (unsupported) install files

$ cd /tmp
$ wget http://www8.garmin.com/software/MapSource_6153.exe
$ mkdir Mapsource-6.15.3
$ cd Mapsource-6.15.3
$ unzip ../MapSource_6153.exe
$ sshfs localhost:/tmp/Mapsource-6.15.3 /mnt

Now use /mnt as install folder and MAIN.msi as install file. This makes you not need an original product to upgrade.
Choose to install more software and select Setup.exe

$ fusermount -u /mnt
$ cd /tmp
$ rm -rf Mapsource-6.15.3

Done. For me 6.15.3 works on all my boxes, even where 6.14.1 failed.
Enjoy!