Build A Linux-Based Wireless Access Point
Part One: http://www.enterprisenetworkingplanet.com/nethub/article.php/3463611
Part Two: http://www.enterprisenetworkingplanet.com/nethub/article.php/3467111
Other Tools: http://hostap.epitest.fi/
Other userful Links: http://www.linux-wireless.org/Wireless/AP/