Can I claim medical expenses for a nondependent. If so, where do I enter the information?

Unfortunately, you cannot claim medical expenses for a non-dependent.  You can claim medical expenses for you, your spouse or a dependent listed on your income tax return.  

What about the non-dependent exception for those who are totally disabled?

There is no specific exception for a disabled non-dependent.

But, he/she may qualify under the "medical dependent" exception: 

If your close relative cannot be your dependent because he had more than $4,300 of gross income, but otherwise would have qualified as your dependent (basically that you & other family members provided more than half his support), then you can include in your deductible medical expenses (on Schedule A) any qualifying medical expenses you paid on his/her behalf just as if he/she was your dependent.