Set the override-redirect flag for the window with the overrideredirect method before mapping it (this is documented in the Tk::Wm man page). Example:

#!/usr/bin/perl

use warnings;
use strict;
use Tk;

my $mw = tkinit;

$mw->overrideredirect(1);   # set the override-redirect flag

$mw->packPropagate(0);      # prevent the window being resized
                            # for this demo
$mw->Button(
    -text       => 'Quit',
    -command    => sub { Tk::exit(0) },
)->pack(
    -side       => 'bottom',
);

# after a delay: 
# withdraw
# clear the override-redirect flag
# re-map the window
$mw->after(
    4000,
    sub {
        $mw->withdraw;
        $mw->overrideredirect(0);
        $mw->deiconify;
        $mw->raise;
    }
);
# NB:
# "Mastering Perl/Tk" mentions that clearing
# the override-redirect flag will not cause
# the window manager to supply decorations.
# This is true, but at least on KDE, clearing
# the flag, then unmapping and mapping the
# window puts decorations in place.
#
# Your mileage may vary.

MainLoop;
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