Technical answer:
The "list" object (ToolsDisplayOrder element) is of the same type as the "loader list" object (DisplayOrder element).
DisplayOrder and ToolsDisplayOrder elements belong to {bootmgr} object and make up Windows Vista/7/8/10 "boot menu".
These elements are lists of GUID's - unique identifiers of objects in Windows BCD.
You can add any BCD object of type application to ToolsDisplayOrder or DisplayOrder using Visual BCD Editor or bcdedit.
Application objects have a type of 0x1.........
Visual BCD Editor displays all properties of BCD elements and objects so advanced users can easily distinguish what is what.
Less advanced users could get a basic understanding of BCD using a short introduction to Windows BCD structure, objects and elements.
The Microsoft reference for Windows BCD is for more advanced users.
A special hidden partition could be used for installation (copy) of a standalone (offline) security scanner. The security scanner should be able to update its virus signatures on run so the whole exercise would have a meaning. This offline scanner should also check itself on start so infection could be signaled !
Every product which can start from a CD/DVD/USB could be installed to a disk partition and later chain loaded from Windows 7/8 boot manager (assuming MBR partition style disk).
The UEFI implementation of Windows boot manager limits the loadable applications to Microsoft EFI applications (and GPT style disks). (But, you can load any EFI application using UEFI firmware boot manager.)