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