It works OK for me:
Code:
use q: @HOMESHR+"\"+@HOMEDIR


Give me:
Code:
Status       Local     Remote                    Network
-------------------------------------------------------------------------------
OK           Q:        \\hmiuklhdfl001\users$\rhowarth\MYDOCU~1
                                                 Microsoft Windows Network


Jooel, what error do you get when the mapping fails? It's not down to something as simple as @HOMEDRIVE being already mapped, is it?