Create another VHD, and attach to another image you already have running (Linux, Windows etc.) now, copy the acronis backup to this new drive in the virtual machine
Once copied, remove the new vhd from that image
Now, attach the vhd as a secondary drive to the image you are trying to create
Now, boot the Acronis disc through the image and it should see the secondary drive available with the image on
Of course, the thing probably won't boot as all of the HAL is different (hence my eventual use of the bare-metal restore addition)
HTH