To help you build an Other Card DLL, the following sample files are provided in the \SDK\Wallet\Samples\OtherCards\VolcanoCoffee subdirectory in the Microsoft® Wallet version 2.1 installation:
You can set up an Other Card component that interfaces with the Payment Selector by using the required tools and modifying the sample source files. You can then test your component by using the Payment Selector control, which you can download and install from http://www.microsoft.com/wallet.