You can but
CommandLine is deprecated and will probably dissapear soon. Instead, you should use
Executable and
Parameters.
See the FCL documentation, and the TProcess section in the wiki page on
Executing External Programs to see them in use.
If for some reason you have to start from a full command line, you can find a couple helpful functions in LazFileUtils: SplitCmdLine() and SplitCmdLineParams()
HTH!