I went to the Ole Miss debacle last week, which was a tough ticket and got in.
What they do is they start selling student tickets at the general admission ticket office based on "the flow" of students coming into the game. If it looks like the student section isn't going to fill up, they will sell as many student tickets as they can on a first come first served basis.
At the same general admission ticket office, they may have some tickets for sale as well that people have sent back because they can't go to the game or whatever. If they have any, they will sell them before the student tickets. Once they have sold these tickets, see the first paragraph. I suggest getting to the game VERY early. About three hours ahead of time or so to get in line.
The good news for you is that according to a student I talked to, the student has only filled up once- and that was the game I went to. Which meant I was screwed for the time being. So, you have a better than average shot at getting a ticket this way.
If worse comes to worse, you could do what I did. Go to one of the unofficial MSU ticket brokers outside and bring KY jelly and a bunch of money with you. I had no other choice but to go this route, but I was able to get a ticket from a nice man named Rico who was more than happy to take my money.
If I were you, I would make sure I exhaust the first two options before I went to Rico. (Captain Obvious)