Case Mod for Internal Radiator

[Zabuzaxsta]

I have a Phantom 410 case by NZXT and I was hoping someone could help me figure out how to mod it so that a 240mm rad could fit in the bottom part of the case next to the PSU. The 2.5" bays are split into two sections, and I've figured out how to remove the lower one so that I have enough room for the rad, shroud and fans. The problem is that I can't figure out how to mount the radiator to the chassis. Ideally, I would like to have the radiator sitting on the floor of the case with the fans on top pulling air through, but I can't find a guide for how to mount the radiator straight to the chassis. Maybe I should try to just mount the fans on the bottom pushing air through the radiator? I'd need two sets of screws to do that, one to mount the fan to the case, the other to connect the fan to the radiator (this seems tricky, as I wouldn't be able to screw in the later type of screw). The other problem is that there is a perforated portion of the floor for a bottom mount fan that the radiator will be covering (and then some) - unfortunately, the screw holes for fans are far too large to be of use for securing the radiator.

Any ideas, or maybe links to a guide for how to generally mod a case for an internal radiator? Should I just punch out a similar 120mm pattern in the floor next to the factory one, or do I need to free up more open space to allow air to flow through the radiator? How on earth am I going to mount this thing over the pre-existing mounting holes for a fan? How do I even make threaded holes in metal; is there a special drill bit for this? Can I get the right bit for the particular screws used on black ice radiators?