mount VM disk image from script

hi
i'm writing script to backup data from my harddisk
i need possibility to mount my VM's disk images in order to backup some data
i've tried to use Parallels Mounter but it's not suitable for scripts:
1) it never finishes once launched from command line
2) it can ask user question using GUI messageboxes, which my script can't control
I've found that actual work made by PEFSUtil, but i can't found any documentation for it.