in exchange admin create a new custom recipient, on the mailbox you want forwarding done on go to the delivery options tab and under Alternate recipient click on modify, find and insert the custom recipient that you just created and click on the check box in the bottom portion of the Alt rcpt option box to deliver only to the forwarded address (unless you want a copy of all mail delivered locally)
List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm
