Dress Code for Online MBA Bi-Annual Residency Requirement?
The good news: you don't need to wear a tie.

I doubt shorts will ever fly for this residency component; as to whether new-looking jeans will work -- you won't know until you have a chance to see what the Romans are wearing.  If you ever get to the point of experimenting by wearing jeans one day -- try it on a Friday the first time and see what happens.

If you get tired of wearing a tailored shirt, you can probably get away with a new-looking polo shirt (i.e. not stretched out, no grease spots).  In warm weather, I see nothing wrong with using short sleeves.  Shirts cut straight across and worn untucked are probably fine too.  But your T-shirts are temporarily going to have to be relegated to after-work and weekend wear.

I do recommend a tucked-in shirt and a jacket for at least the first couple of days.  Your goal is to start out the program with no personality -- without sticking out and looking like someone who has wandered into the wrong picnic or the wrong classroom.

In short, bite the bullet and enjoy the fact that you don't need to wear a tie.