As Dansdad mentioned for a more specific request, it's best to call in and have it added to your reservation. Also, you can fax your requests in around 6 days before arrival. There is a POR/POFQ Fax thread that you can check out as well.
Here is a site that shows the resorts online check-in options.
http://wdwprepschool.com/how-to-get-the-disney-world-resort-room-requests-views-rooms/
In case DIS blocks the URL

For POFQ GV the options are:
Corner Room, Second Floor, Near Elevator, Ground Floor or Near Trans.