Changing pivot point of svg mesh group with 'applyMatrix4OnOrigin'?

I’m importing svg’s with SVGLoader.
I get a group that represent the imported image.
( a group of meshes).
How can I use applyMatrix4OnOrigin to set the transform origin to the center of the group?
I found out about that method after reading people discussing how to change pivot points.

I’m using this code with no results:

                    function setPivot(item)
                        let itemMatrix = item.matrix;
                        let itemOrigin = [ SVGheightHalf,SVGwidthHalf, 0 ];
                        item.applyMatrix4OnOrigin( itemMatrix, itemOrigin );


EDIT: I found my answer for centering objects in a group here:

Although I found an answer to my issue, in still curious about the exact implementation if the above mentioned method. If any examples could be provided, I’d be much obliged.