I was wondering how exactly to approach telling my college's residential life/housing office that I am transgender and how rooming or being assigned to a roommate would work. How can accommodate to my needs? I need help writing out an E-mail to them. I just don't know how exactly I'm supposed to say it. Do I just say flat out or..?
Any advice would help. I'm going into my first year of college and I'll be dorming.

I would just give the housing department a call -- you don't have to tell them your name right away.  Most Universities that I have heard and come in contact with is more than willing work with you.   Unless your going to Florida State University - which beginning this year will have housing for Transgender folks.

Also contact the Dean of Students and tell them of your situation. Sometimes they may give you a one occupancy room or bunk you with a sympathetic trans allie of your gender identity. The week before Seminary started for me, we had to go to a retreat. I brought this to the Deans attention and I bunked with another girl who was sympathetic.

Def explore those options too. Personally, I don't think I would be too thrilled bunking in a dorm full of trans people. I love trans, I'm trans myself, but when you get trans together in a room....well...fight fight fight fight lol.

Do you mind if I ask where you're going to school?
When I had to come out to housing, I was fortunate enough to be able to go meet with them and tell them in person.
In any case, the advice already given is worth following.

-Richie

Most unversities will work with you.  You are not the first one to be trans at their school.  Many will give you a single room in a coed dorm. 

I'm going to Stevens Institute of Technology. I haven't heard of transgender housing from them. They do have coed dorms though. I'll ask them if it's possible for me to get a single room.

When I got to college, my mom called the director of health services and asked them what accommodations they could give me. If you speak to someone on the health services staff of your college, it might give you a better chance of coming into contact with someone who understands what "transgender" means and knows how to handle these situations.