Amorphous Cell Construction: How to keep a nanoparticle inside a simulation box when soaking with water?

I build a nanoparticle and want to soak it with water using Amorphous Cell.

Q1: When using Construction function, how can I keep the particle at (not neccessary exactly at) the center of the simulation box?

Q2: When using Packing function, how can I create a simulation box surrounding the nanoparticle so that water can then be packed in?

Thanks