Well, even if there was a walk way, given the size of AK I doubt that you'd really want to walk to AKL after spending the day walking around a very hot and sometimes hilly AK!
We had a very quick and entertaining bus ride from AK to AKL; it was nice to sit too.
I am aware of the following walking options at WDW:
MK - to or from the Contemporary (We did this our Chef Mickey's ADR)
Epcot - Apparently from any of the Boardwalk area resorts
MGM - not sure
AK - none that I am aware of
DTD - from SSR DVC propertry