Are you asking if it is possible to book an unusual route that is not normally permitted, or are you asking if a route is permitted in the Routeing Guide?
All sorts of unusual routes can be booked simply by using a "via" point that you want, and seeing if the website will allow the ticket to be bought. If it doesn't allow it, it's probably not a permitted route (but it may be) and if it does allow it, it's probably a permitted route (but may not be). The booking engines are nearly always right, but where they are not, travel is still permitted on an itinerary that you book.
Mapped routes are available (as defined by the Routeing Guide) on the following maps (using Lincoln Central as the appropriate Routeing Point)