There are some dishes out there you can get at Chinese restaurants that are little more than steamed meat/veggies and possibly some rice. See if there are any items like this on the menu. And as far as MSG goes - I'd make that your 2nd priority - avoiding breaded/deep-fried dishes cooked in unknown oils should be top priority - a little MSG is far less important than the above. But looked for the steamed meat/veggies.
Anyhow, I've been in the same spot at work. I'd strongly suggest seeing if you can get a copy of the menu ahead of time, so you can form a plan. Makes it easier if you're not frantically searching while your guests are waiting to order.