You can't turn off wireless feature, but you can use your Time Capsule to extend your wireless connection, so it won't be used as another "router" but it will extend your Wi-Fi network. See > http://support.apple.com/kb/HT4262
You cannot use the extend option with another brand router.. so the above will not work with the BThub. And WDS btw is now not used on the TC or apple routers.. haven't ever since N wireless came out.. the above article is for G wireless routers of yesteryear.
The best way to do it is bridge the TC.. that is router bridge not wireless bridge.. and simply plug it by ethernet into the BT hub.
You can then setup wireless however you want.. it can reinforce the existing wireless. Simply use the same name (SSID) and security setting.. (should be WPA2 Personal ie AES).. and passkey.. but if you want to make it sure, then lock the wireless channels. This is called a roaming network.