Um, while there might be a way to technically make this work, it sounds like it would either be expensive or useless.
If the AP is connected to the network, then by plugging the AP into your wired card, you're essentially creating a wired connection. The AP is a router in this case and the wireless is irrelevant.
If you do manage to make the AP into an ehternet card, you'd need a second AP to act as the connection to the network. That strikes me as expensive.
Instead of pursuing this course, why don't you post the details about the card you want to use and maybe we can point you in the proper direction. Wireless can be a pain in Linux, but there is significant support out there.