There is an option for that in FARR.
Go to options -> Launching files. At the bottom, there is a Misc section, enter
shellexec $$1 and you're good to go.
ScreenshotYou then just type in your command in farr and press enter. The trick is that if there is no results FARR will launch the search string using cmd.
Usually when you type in a shell command with parameters etc it will not match any documents so you're good to go. For example ping google.com, shutdown /l etc
If you execute commands that match some files you can use an alias. For example, create an alias with regular expression
^cn (.*) and result
shellexec $$1, then you type in
cn <your command with arguments> and it should execute.