lacymuw: I am a freshman in college, and still don't know how to communicate with my mother.
First, decide what you want/how you feel. Then figure out whether it is reasonable. If it is reasonable, talk to your mother in a polite fashion about what your want/how you feel. At that point, the balls in her court. If she doesn't change, then you have to decide to either put up and shut up, or go off on your own. This is a valuable skill for dealing with relationships.
lacymuw: I just try to explain to her that the way she behaves around my friends is different than when it's just the two of us, and I don't want her to be my friends' friends.
Doesn't everyone act differently depending on who is around? Parents still have the natural human desire to be liked by others. Your mom wants to be liked by your friends. It's pretty natural.
lacymuw: I excitedly read Prudie's response to this collumn looking for a great way to communicate with her, and all I got was the classic, "Get your own house!" line.
Were you honestly expecting good advice from an advice columnist?!? That's simply not going to happen. Even if the columnist were writing with the idea of dispensing real advice and not for entertainment, every situation is different and the devil is in the details. The way I learned to deal with my mother may not work for you because your mom is different. This is why parenting is difficult. What works for one kid might fail on the next.
That being said, as an adult you really don't have a lot of options besides deciding to put up with it, argue a lot, or get your own place.