I guess there is no standard way for it.
You could write a program to download a BPC hierarchy to a flat file.
Then follow the standard BW procedure to load the hierarchy to the info objects
The following link will give you an idea on how to generate a flat file from a hierarchy.
You need to tweak the code a little to utilize it BPC hierarchy and BPC objects
http://www.element61.be/e/resourc-detail.asp?ResourceId=189
The following link will tell you how to upload a flat file hierarchy to a BW info object