It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
import crafttweaker.util.IAxisAlignedBB;

You can create a IAxisAlignedBB object yourself by using the following methods:

ZenScript
 Copy
IAxisAlignedBB.create(double minX, double minY, double minZ, double maxX, double maxY, double maxZ);
IAxisAlignedBB.create(IBlockPos pos;
IAxisAlignedBB.create(IBlockPos pos1, IBlockPos pos2;
IAxisAlignedBB.create(IVector3d min, IVector3d max);

The First method allows you to create a position at the given coordinates.

ZenGetter	Type
ZenGetter minX	Type double
ZenGetter minY	Type double
ZenGetter minZ	Type double
ZenGetter maxX	Type double
ZenGetter maxY	Type double
ZenGetter maxZ	Type double
ZenGetter center	Type IVector3d