Four-arg select returns -1 if it is interrupted, 0 if timed out. Using that and Time::HiRes, here's a demo,

#!/usr/bin/perl    # file: sigdemo
use warnings;
use strict;
use Time::HiRes qw/gettimeofday tv_interval/;

$SIG{INT} = sub {};

my $timer = shift;
my $start = [gettimeofday];
{
    last if $timer <= 0;
    $timer -= tv_interval($start), redo
        if select undef, undef, undef, $timer;
}

print "*Yawn* what time is it?\n";
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(Untested, no AIX here). That is meant to sleep through Ctrl-C keyboard interrupts for X seconds given on the command line.