The 887 AP IOS runs independently of the router's IOS. They are almost like a separate router and AP connected via an ethernet cable. That why you have to use the service-module wlan-ap 0 session command to reach the console via wlan-ap 0.
If you have a Wireless controller, the AP can actually be controlled/configured via the controller.
You can use the router's IP address for management and then connect to the AP's console from there but since the AP and router are running independent images, there is no easy solution.