Get ReloKick and TurboPAL
its the best option or get a ROM switcher and put the 1.3 ROM and the 3.1 rom...most people would tell you you dont need the rom switcher if you have 3.1 because 1.3 is built in. But I believe it will work better.
But get Relokick.it turns your A600 into a 1.3 machine...........you even see the hand with the disk like on an A1000 or A500.
But the MEGA most BEST way...........is to get WHDLoad.it lets you install the games onto Harddrive and even makes it work even if you dont have ROM 1.3