use Win32::GuiTest qw(:ALL);
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Specifically, i was interacting with the LPR printing program from the command prompt. You didn't cite any specific code up there so I'm not sure exactly what you are trying, but I got LPR to interact with me on the command line with some form of the code below:

use strict;
use warnings;
use Win32;
use Win32::Process;
use Win32::GuiTest qw(:ALL);

# start new command prompt
my $process_object_cmd;
Win32::Process::Create( $process_object_cmd, "C:\\Windows\\system32\\c
+md.exe","",0, NORMAL_PRIORITY_CLASS, ".", ) or die "Could not spawn p
+rocess\n";

&Set_Focus( "Command Prompt" );

my $ipAddress = 'test';
my $printName = 'test';
my $file = 'test';

#
#  Below in the qq[] is where I'd try sending some input to 
#  whatever DOS app you're going for...here I'm printing
#  to LPR...
#
SendKeys( qq[lpr -–S $ipAddress -–P $printName filename $file] );
SendKeys( "~" );

#
# If you need to send more keystrokes or whatever, check
# the documentation, pretty much any keyboard stuff is
# possible with that module
#

# Subroutine: Set_Focus
# Parameters: window Name
# Description: Takes the name of a window, uses tools from GuiTest to 
+set focus
#                to that window so that we may send it input.  Returns
+ window ID
sub Set_Focus {
    my $windowName = shift;
    
    my $retryCounter = 0;
    
    my @windows = FindWindowLike( undef, "$windowName", "" );
    
    unless ( @windows ) {
        
        @windows = FindWindowLike( undef, "$windowName", "" );
        
        sleep(1);
        
        $retryCounter++;
        
        if( $retryCounter == 5 ) { die "Unable to gain control of $win
+dowName...\nScript exiting...\n" }
    }

    my $focusError = (bring_window_to_front( $windows[0] ));

    return( $windows[0] );
}

# Subroutine: bring_window_to_front
# Parameters: window ID
# Description:  Takes in window ID, and sets it as foreground window
sub bring_window_to_front {
    my $window  = shift;
    my $success = 1;
    
    unless ( $window ) { $window = "notyet" }
    
    unless( $window eq "notyet" ) {
        SetActiveWindow($window);
        sleep(1);
        SetForegroundWindow($window);    
    }

    if ( $window eq "notyet" ) {
        #print "* Could not set the window id: $window active\n";
        $success = 0;
    }
    return $success;
}

[download]

Update
This example will probably just print the LPR help stuff, since I use 'test' for all the connection strings, just thought I'd let you know. Also added a couple extra comments in the code...