phibuilder is fine. It reads your iobj file and gives you a hierarchy of parts.

you adjust that hierarchy by moving parts around till it appears correct.

Then from within poser you use the file menu option , load the phi file and it will create the figure in the new figures folder.

You then load it and adjust centers as required.

You can use the hierarchy editor in poser to do the same thing, use the button at the bottom to create the figure.