BEGIN {
my $path=$0;
$path=~s{[^\/]+$}{libs/};
}
use lib $path;

##</code><code>##

<virtualhost *:80>
# ...
PerlSetVar libpath "/path/to/your/libs/";
</virtualhost>

##</code><code>##

BEGIN {
my $path=$r->dir_config("libpath");
}
use lib $path;