P7 Mag Dropin Mods?

[Rusty Joe]

http://www.dealextreme.com/details.dx/sku.14413

What will I have to have/do to get this to fit with my 3 D Mag?

 

[BREAM]

There is some info in the feedback on the site but I don't know if it applies to the 3d mag. I wouldn't mind knowing as well so I can convert mine.