macOS

Source: https://serverfault.com/a/1000645

It's now 2020, and these 10-year-old instructions almost worked. Here's what I did to mount an old Backup Image from Windows 7 on my Mojave Mac, based on the accepted answer from Jan Bernlöhr, as well as the script in the question.

• Install osxfuse (the successor to macfuse)
• Install VirtualBox
• Download the vdfuse source code (vdfuse.c) from https://github.com/Thorsten-Sick/vdfuse (currently at v83 - the original link is pegged to v80).
• Download the VirtualBox headers, but you have to get a version from 2012. I used the following command: svn co -r '{20120801}' http://www.virtualbox.org/svn/vbox/trunk/include/
• Use the following build instructions, adapted from the question, but with a few small alterations (64-bit build, and newer VirtualBoxes don't seem to have VBoxREM.dylib:

infile=vdfuse.c
outfile=vdfuse
incdir="$(pwd)/include"
INSTALL_DIR="/Applications/VirtualBox.app/Contents/MacOS"
CFLAGS="-pipe"

gcc -arch x86_64 "${infile}" \
       "${INSTALL_DIR}"/VBoxDD.dylib \
       "${INSTALL_DIR}"/VBoxDDU.dylib \
       "${INSTALL_DIR}"/VBoxVMM.dylib \
       "${INSTALL_DIR}"/VBoxRT.dylib \
       "${INSTALL_DIR}"/VBoxDD2.dylib \
      -o "${outfile}" \
      -I"${incdir}" -I"/usr/local/include/fuse" \
      -Wl,-rpath,"${INSTALL_DIR}"  \
      -lfuse_ino64  \
      -Wall ${CFLAGS}

• Mount the vhd disk

  sudo ./vdfuse -tVHD -w -f/Path/To/VHD /Path/To/Mountpoint

• Attach the virtual partition blockfiles

  hdiutil attach -imagekey diskimage-class=CRawDiskImage -nomount /Path/To/Mountpoint/PartitionN

• Mount the virtual partition

  mount -t YourFS /dev/diskK /Path/To/ParitionMountPoint

Miraculously, this works a charm!