#!/usr/bin/perl
use strict;
use warnings;

BEGIN {
	use Sys::Hostname;
	my $hostname = hostname;

	if($hostname eq 'devserver'){
		use lib '/foo/bar';
	}
	else {
		use lib '/bar/foo';	
	}	
}

# ... And Some/Module.pm being found in those paths set in BEGIN block
use Some::Module;