I've posted some pics to the Flickr group of the boy version of the 2+2 top if anyone is interested. It is kind of tricky to explain how I did it all, but it was a very easy alteration to do. Of course I didn't take any pictures as I went but let me know if anyone would like to know the steps I took to make it and I'll try to explain more clearly!
Pics here:
http://farm5.static.flickr.com/4108/5205891224_0698cc85a1_m.jpg
http://farm6.static.flickr.com/5088/5205295545_5dc832f611_m.jpg
http://farm5.static.flickr.com/4113/5205897478_22429e0461_m.jpg
http://farm5.static.flickr.com/4127/5205901596_8dff1163e4_m.jpg
Thanks to those who helped with my questions about removing the buttons at the back- I did this and there is still plenty of room to fit it over his head.