The rows are 2.54mm apart, which is fine if you want to fit a 50 way box header and use a 50 way IDC connector to 50 way IDC edge connector cable, but not fine for fitting this type of edge connector. Hence a little bit of hackery being necessary when fitting the edge connector directly.
I found when building a board for someone that it is easier to leave one row of pins straight, and use needle pliers to bend the other row's pins into a sort of Z shape. I'll post a picture soon.
Also, please note that the edge connector must be fitted so that it comes out of the '''back''' of the board. Please check the pictures of the finished boards and ensure you get this right. If in doubt, contact me.