Hi Medicated,
My 'lost' career was that of being the Dean of Student Services for a college. On the job and now as an independant contractor I have written a lot of policy manuals for colleges and universities among others.

Generally 'for medical reasons' backed up by a doctor's note is all that is required. They don't need to know the specifics. Make your request short and sweet. I wouldn't even talk about scheduling accommodation. That will be something you will discuss in person.

Keep it short and simple.
'I am currently a 4th year student in the ....... program. As per the Leave of Absence policy number.... I am writing to request a 2 week medical leave of absence to begin immediately and end September 2, 2010. A letter from my doctor is attached. I look forward to hearing from you at your earliest convenience. Please contact me if you require any further information. Thank you for your time and attention to my request.'

Less is more in these kinds of initial communications. Put too much in the letter and it can work against you sometimes.

Meanwhile become familiar with the Appeals process should you be refused on first request. It is very unlikely you will be refused but if you are there will be policy for an appeal.