this is what i got reply from University for request of missing orientation:
Hi Haseeb,
Got your VM this monring.
You are okay to come as late as September 3rd. After that I would encourage you to start in Winter 2013 semester. Without orientation student success rate drops considerably. Each semester costs about $7500 plus living expenses.
We always try to accommodate late arrivals but emphasis is on students. My best advise is to participate in orientation and start your new career right.
Choice is yours.
Thanks,
Amit