According to the latest Alister McRae newsletter Markku Alen’s name appears as a confirmed starter.
From the newsletter
”Joining Alister and his father Jimmy at this September’s McRae Stages in Perthshire will be four former WRC Champions.
Ari Vatanen with Co-driver David Richards, Stig Blomqvist, Hannu Mikkola and Bjorn Waldegard will compete in Round 8 of the Scottish [...]

  
Bjorn Waldegard is the latest name confirmed for the McRae Stages which takes place in September. Waldegard will pilot a Francis Tuthill Porsche 911 on the event. The rally is certainly shaping up to be the event of the year with quite a number of stars confirmed and many still to be added.
Names so far confirmed are; Ari Vatanen [...]