The easiest way is to do that using WMI. A bit of Googling tells me that you can get the command line of any process using WMIC:

WMIC PROCESS get Caption,Commandline,Processid
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Then, you just have to go through all lines in your script and you have the process id.

See perlop for how to get the output of another process.

Maybe you want to use DBD::WMI to avoid running an external program. Most likely, the SQL would be

SELECT
    Caption
  , CommandLine
  , ProcessId
FROM
    Win32_PROCESS
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