Add the following to beginning of checksetup.pl:

BEGIN { $SIG{__DIE__} = sub {
    my ($a) = @_;
    if ($a =~ /Can\'t locate (\S*).pm in/)
    {
        my $i = 0;
        my @c;
        while (@c = caller($i++))
        {
            if ($c[3] =~ /\(eval\)/)
            {
                die @_;
            }
        }
        my $fn = $1.'.pm';
        my $m = $1;
        $m =~ s/\//::/gso;
        print "Perl module '$m' is needed to run Bugzilla. Install it from CPAN? (Y/n) ";
        my $k = <STDIN>;
        if ($k || $k =~ /y|^\s*$/iso)
        {
            system("cpan '$m'");
            exec("perl '$0' '".join("','", @ARGV)."'");
        }
        else
        {
            die @_;
        }
    }
}; }