For what it's worth (if anything) I discovered there's a native runperl.bat in perl's bin folder and the bin folder is in my (search) path.
To launch/run a current doc perl script (a substitute for typing in the command console)
^!Shell "^$GetShort("^**")$" "runperl"
evidently that passes the current doc's filename to runperl.bat which in turn gets the script/arguments etc. into perl
(I guess), I never did understand batch files very much.
perhaps NoteTab's ^!runperl somehow utilizes runperl.bat