Those who have performed a quad rail mod on the G&G Combat Machine CM16 AEG's?

[Special Ops]

I understand that in order to install quad rails on my G&G Combat Machine Carbine Light (shown in the picture below), I may need to perform some modifications in order to get the quad rails to have a drop in fit. I've decided to give it a try and I'm thinking of going with the Matrix quad rails that Evike sales.

 

My question is for anyone who has performed this modification on a G&G Combat Machine CM16 for the use of non-free float quad rails. What all was involved in the modification process, what brand quad rails did you use, and were you successful at installing the quad rails?