Yes you can use any travel agent to book a GU42 ticket, I have just done this to Delhi from D to F. Even better, they use discount fare buckets for this, rather than award buckets which are impossible to find.

Follow this post: http://www.flyertalk.com/forum/showthread.php?t=528503

Print out the travel agent instructions you will find and give to the agent. Without this, mine wouldn't have known what to do. Happy travels.