Don't wear A&M stuff; just not worth the price of a ticket to do. Here is exactly what you need to do (assuming that the consensus is right that you're looking to do more than "crash" at her place the nights before and after the game): Tailgate with her and friends before the game in Nebraska gear. Half an hour before kick-off, find a scalper and get a cheap ticket. Go to game and scope out other girls in your section. During timeouts, halftime, etc. explain that your looking to see what's going on after the game. Find other A&M girl to hang out/"crash" with. Explain to your friend (after the Nebraska victory) that you met some cool people to hang out with for the night and she should come out with y'all. Go out, see which one is feeling you more and make it happen, although I wouldn't leave too many of my luggage at friend's place in case you go home with the broad that you met at the game...she might not be too happy.
Benefits: Cheap ticket, not compromising your own or you team's integrity, meeting new friends.