You can use a SRV record for exchange Autodiscover services, just create a srv record named:
Service: _autodiscover Protocol: _tcp Port Number: 443 Host: [Hostname of the server]
Eg.
Host: _autodiscover._tcp.kasperk.it, Port 443, host: mail.kasperk.it
source: http://support.microsoft.com/kb/940881
You can test the configuration here: https://www.testexchangeconnectivity.com/ choosing Outlook Autodiscover