|It is possible but you would need a second Wireless Network interface in the computer that connects the the Access Point. You cannot use the same interface for the access point and Ad-Hoc at the same time. You would then need to configure Internet Connection Sharing on the computer and bridge the two wireless interfaces. All a bit complicated.|
Better to find out why the Nintendo wont connect to the Access Point and if necessary, change the configuration so both the Nintendo and the Computer can connect.