[CentOS] control outgoing IP address?

I'd like to consolidate some services that have been assigned by IP 
(dns, syslog etc.) onto one machine by giving it IP aliases to accept 
connections for the old addresses until all the references are fixed. 
However, I'd like to have it use it's original IP as the source for 
outbound connections.  Where do you control that?

-- 
   Les Mikesell
    lesmiksell at gmail.com