@garmin62

First you have to install BaseCamp v3.0.6 (the current release) from Garmin. That install includes several language DLLs including Swedish.
Then just backup the original BaseCamp.exe and use the patched v3.0.6 EXE instead. The path would normally be like "C:\Program Files\Garmin\BaseCamp".
If you have Swedish settings it will be Swedish even with the patched EXE since it uses the DLL files for language support.