Aside from mispelling "lib", the order of execution is totally wrong. Your code is equivalent to: 
BEGIN {
    require Config;
    Config::->import();
    require lib;
    lib::->import('./lib64/perl5/5.8.5/x86_64-linux-thread-multi');
    require lib;
    lib::->import('./lib64/perl5/site_perl/5.8.5/x86_64-linux-thread-m
+ulti');
    require lib;
    lib::->import('./lib64/perl5/5.8.5/i386-thread-multi');
    require lib;
    lib::->import('./lib64/perl5/site_perl/5.8.5/i386-thread-multi');
    if ($Config{archname64}) {
        # empty
    } else {
        # empty
}

[download]

Note that all four directories are added to @INC unconditionally because use statements are executed as soon as they are compiled. Fix: 

BEGIN {
    use Config;
    require lib;

    if ($Config{archname64}) {
        lib->import(qw(
            ./lib64/perl5/5.8.5/x86_64-linux-thread-multi
            ./lib64/perl5/site_perl/5.8.5/x86_64-linux-thread-multi
        ));
    } else {
        lib->import(qw(
            ./lib64/perl5/5.8.5/i386-thread-multi
            ./lib64/perl5/site_perl/5.8.5/i386-thread-multi
        ));
    }
}

[download]

Update: Markup changes.

In reply to Re^2: How to instrust Perl to load the right modules based on architecture? by ikegami
in thread How to instrust Perl to load the right modules based on architecture? by sunshine_august

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