Scylla is on the spot you cannot apply through Ghana without residing there legally. You can try your luck by applying in Nigeria immediately. In recent times I know of 2 people who applied in Lagos Nigeria but the communication they got from the embassy showed that even though they submitted their application in Lagos,it was transferred to Ghana(may be to reduce backlog in Lagos)and of course it came back early. You may be lucky to be selected as part of those to be transferred to Ghana for treatment even though you submit your application in Nigeria and you need to do it on time for September 2014 entry goodluck!