Hi,
I had the same "problem". It seems to me that the hole itself is more or less the right size, but the screw holes are slightly displaced to one side. I just widened the connector hole a bit (1mm at most) with a Dremel. I have everything mounted in my car and unfortunately I didn't take any pics of my new harness...but I can tell you, It took me around 2:30 hours to make it...but it was worth it! The only thing that I'm not happy about is that I didn't have coloured wires, so all the cables that come from the ISO connector are red... :P

side note: I didn't put a fuse on the empeg harness; I played with a with a multimeter and found out that my car has a fuse for the radio only on the same wire where the empeg has his; so I just replaced that one with a 3A fuse. Is that allright or do you think I'm playing with fire?