If the script is a purely command line program that takes its inputs from stdin, you can avoid IPC::open3 by feeding the required interactions to via a pipe.

Say the script requires two lines of input, like this one:

#! perl -slw
use strict;

chomp( my $interact1 = <STDIN> );
chomp( my $interact2 = <STDIN> );
print "Got: $interact1 $interact2";
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Then you can feed it the required inputs and retrieve its output like this:

C:\test>perl -E"$p = open I, '-|', '( echo fred & echo jim ) | interac
+t.pl'; say for <I>;"
Got: fred  jim
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This often will not work for programs that expect passwords.