You'll be best served to wrap your Perl script into a batch file wrapper script and then allow OpsMgr to call that...
This would be the contents of your batchfile:
perl "C:\Documents and Settings\administrator\Desktop\SomeScript.pl" > "C:\Documents and Settings\administrator\Desktop\output.txt"
and then have OpsMgr call that batchfile (this assumes Perl is in your PATH)
Let me know if you need any more help