I'd imagine you could just use the built in Run an Application command in Voice Attack itself. Path to CrewChief in the first line, and PCARS_NETWORK in the parameters line. Shouldn't need a batch file.
If it matters, though, your proposed code is close. Remove the second ECHO; that will just display the line to the command prompt, not actually run the program. Also, if your path to crewchief.exe has any spaces in it, you should wrap the entire path in quotes.
@ECHO OFF
"C:\Program Files\Crew Chief\crewchief.exe" PCARS_NETWORK