At the end i made it:
And it doesn't even lag.
First i exported the mk7 kcl to obj, then i converted it to a 3d land kcl with CollisionsMng.
Then i converted the mk7 bcmdl to obj (it's a different mesh than the kcl) end reduced every big texture of 75% (from 128x128 px to 32x32) and then used the model import function from the editor to get an szs, WITHOUT the nw4c toolkit.
Finally i added the entry to the CCNT.
At the end i copied the CCNT in the SystemData folder, the szs in the ObjectData folder, quickly made a stage and it worked.