how do i change my hull size for map entity collision detection to a desired size?

with c_setminmax(my) you set the hull size to the size of the entity.
(Maybe you have to set a wait(1) before that).
If you want to set your own hull size use
wait(1); // wait 1 frame after creation
vec_set(my.min_x,vector(-50,-50,-50);
vec_set(my.max_x,vector(50,50,50);
I hope that helps