It works for me on my Debian 7 beta amd64 host running WS 9.0.2... I installed the guest OS from Mageia-3-beta4-dual-CD.iso, choosing Other Linux 2.6.x kernel 64-bit as the guest OS type. I think I bumped up the size of the virtual HDD but otherwise chose defaults throughout the New Virtual Machine Wizard and through the installation. I'm not sure how Mageia's "dual" media decides on the arch to install, but I ended up with x86_64.
How does that screenshot compare with your VM's configuration there? Am I correct in understanding that the failure you're seeing would have occured at the "cp" command in my screenshot?
Cheers,
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Darius