You need to set against vertices or a set height and distance from player or whatever is picking it up.

So sort out how you are going to do that first.

Next, you need to set to the position same as you would when glueing camera to player with vec_set.
Then you need to tell it that it moves with you, via offset (checkout thanks (tanks) in one of the earlier Aums for attaching rotating gun barrel to tank) and my.frame.

Verice attach is solid and if you tit, the box has to as well, so you need to make it do that too.