To the original poster, I found that I was only seriously considered for a GSA by getting AWAY from the front lanes and pulling a bunch of sales floor shifts. They tend to forget you are there when you are a cashier because they don't hear you on the walkie responding to call buttons, phone calls, etc.. Once they started hearing things like "this is targetismylife09, I can grab that call button" they take a little more notice. It's not right, I know, but that's how they think.
Of course you can also take that to the extreme and annoy people to death like one sales floor TM used to do! She would literally announce over the walkie every time she did anything! We couldn't stand her, but she also got promoted to GSA. I used to joke that I was going to get a walkie for a cashier shift and announce to the LOD every time I finished checking out a guest so I could be like her!