Associate a private key with the X509Certificate2 class in .net

Associate a private key with the X509Certificate2 class in .net

I'm working on some code that creates a X509certificate and a
public/private key pair. The public key is added to the certificate and it
is sent to an CA which signs it.
The returned certificate is then accessed through the
System.Security.Cryptography.X509Certificates.X509Certificate2 class. Now
I want to use this certificate to initiate a secure connection with other
clients. Therefore I use the SslStream class. To start the SSL Handshake I
use this method:
server.AssociatedSslStream.AuthenticateAsServer(
MyCertificate, // Client
Certificate
true, // Require
Certificate from connecting Peer
SslProtocols.Tls, // Use TLS 1.0
false // check
Certificate revocation
);
This method requires that the private key is associated with the
certificate. Of course the certificate returned by the CA does not contain
a private key. But it is stored as .key file on the harddrive. The
X509Certificate2 class has a property called PrivateKey which I guess will
associate a private key with the certificate, but I can't find a way to
set this property.
Is there any way I can associate the private key with the .net X509 class?