The mfrc522-netmf code is build for the MicroFramework and its not the code but the PIN numbering that is not compatible withe the Raspberry Pi
One way is try and copy the code into your project and just replace all the
Cpu.Pin with the actual RaspberryPi specific static ones.
That code "should" then be able to work on the SPI since the SPI is the same implementation on any device.
For more infomration on working with SPI you can look at this to see how it communicates on IoT on the Pi - There is more information on the SPI here and a whole bunch of samples here
It not really that difficult to port it over you may just need to invest some time for it. And when you do get it working, please consider pushing your code to the IoT github or host it your self. More people can use it and improve it then.
A good sample is here - Try and follow how the SPI device is used. - In particular the