I'm actually the developer that originally implemented property sheets in Visual C++ back in VS 2005 (although I'm not responsible for the mess that is the VC++ project properties dialog). Caveat: I stopped working on VC++ after 2005, so below may not be entirely accurate for your version.
In the Property Manager, you should be able to multiselect all of your project configurations in all projects and add a new property sheet. This will automatically inherit those project configurations from the same property sheet. In that property sheet, set the boost include and library directories directly or use a macro for BoostVersion and BoostDir and use those macros in the property sheet's properties.
Provided that the project configurations have "inherit from parent or project defaults" checked (this controls inserting $(Inherit) vs $(NoInherit) in 2005/2008 and %(<propertyname>) in 2010/2012) for those properties, you should see any project-specific properties set in the project configurations prepended, by default, to the values in the property sheet.
You can confirm this by going to a project and checking the compiler's "Command Line" tab to see if the switches are what you expect.
Edit: note that there are two types of properties in VC++: "single-value" and "multi-value". An example of a single-value property is the compiler's warning level. The value on the command line for a single-value property comes from the first place in the property inheritance chain that specifies it, starting with the project configuration, then the property sheets, then the built-in default in the project system. An example of a multi-value property is the compiler's include directories. Multi-value properties get concatenated with their parent property sheets unless $(NoInherit) is specified (2005/2008) or %(<propertyname>) is not specified (2010/2012). Thus, by default, you should see the boost paths showing up in your project settings provided they have intentionally not inherited the property from the property sheet.