Personally, I've never done it and I don't know enough about exchange to tell you the particulars of what's required, but I can explain the process and what needs to occur.
What you will essentially need is this:
1. The ability to forward email from the Exchange mailbox to either the automail.php or automail.pl file - this would be on the same server where the Exchange server resides.
2. The automail file must then be able to execute and connect to the remote osTicket host on port 80 to pipe the email into the system over HTTP.
You'll have to set up an API key in osTicket for the automail file and edit it to add the key.
So you don't necessarily need to have a web server also running on the Exchange server box, but you do need to be able to make that connection to the remote web server, and you will need either PHP or Perl installed on said server to execute the file.
Of course, this also assumes Exchange is set up in such a way to allow you to forward email directly to the file/script and not just another mailbox. As I said, though, I don't know enough about Exchange to tell you how to do this part (or even if it's possible). Hopefully, though, this at least helps explain the process a little.
Alternately, a more simple solution would be to use email polling and connect to the exchange server that way, pulling email at regular intervals via the task schedular. It's not quite as real-time, but if you run it every 5 minutes or so, it's not so bad.
If you haven't read the Wiki docs on routing incoming emails (they may or may not be of much help to you at this point) they can be found here: http://osticket.com/wiki/Email_Settings#Routing_Incoming_Emails(http://osticket.com/wiki/Email_Settings#Routing_Incoming_Emails)
