It will work right out of the box as long as the flaresolverr folder resides in the system drive directory e.g. c:/flaresolverr. The service will set the hostname environment variable to 127.0.0.1 so apps like Jackett can interact with it e.g. http://127.0.0.1:8191. Alternatively, you can modify the commands from the source code to your liking and rebuild the solution.
Instructions to install this service:
1.) Open cmd with administrative privileges
2.) cd C:\Windows\Microsoft.NET\Framework64\[latest folder version] (32-bit version is in the ..\Framework\.. folder)
3.) InstallUtil.exe [service exe path] e.g. C:\flaresolverr\service\FlaresolverrService.exe