The snipet of code that pg posted is pretty close to the idea except, i need to be able to pause/resume/exit the 'for' loop from the gui at will..

Building on pg's example, adding pause and resume is fairly simple:

use Tk;
use Tk::ProgressBar;
use strict;
use warnings;

my $count;
my $pause = 0;

my $mw = new MainWindow(-title => "demo");
$mw->Button(-command => [\&a_long_process, \$count], 
            -text => "A Long Process")->pack();

$mw->Button(-text => 'Quit',
            -command => sub{exit})->pack();
$mw->Button(-text => 'Pause', 
            -command => sub{$pause = 1})->pack();
$mw->Button(-text => 'Resume', 
            -command => sub{$pause = 0})->pack();


my $pb = $mw->ProgressBar(
        -from => 0,
        -to => 100000,
        -blocks => 100000,
        -colors => [0, 'green', 30000, 'yellow' , 60000, 'red'],
        -variable => \$count
)->pack();

MainLoop;

sub a_long_process {
    my $hash = {};
    for (0..100000) {
        $hash->{$_} = $_;
        $count ++;
        $mw->update(); 
        if ($pause) {
            while(1){
                select(undef,undef,undef,0.1);
                last unless $pause;
                $mw->update(); 
            }
        }
    }
}
[download]

I used select for subsecond sleeping, Time::HiRes could also be used.