hey,
I have checked out your requirements and it could be done very easily and I have applied it to my own site for testing purpose and it works out but takes a little time depending on your web hosting providing site. Its just 5 minutes work I just need to update the sub domain and change the DNS record . I do not require any money for this work , just you pay $5 to free lancer,rest depends on you, if you want you could pay else there is no such compulsion.I need good reviews if this work is done from my side as I'm new to free lancer.
I assure you that this will be done in least time it would just take to change the DNS. I could do this work with great ease and could tell you the every possible steps anytime you want after completing this work.
waiting for your responses
with regards Naval Sharma.