Export CngKey in PKCS8 with encryption c#

How can I export CngKey to PKCS#8 with encryption?

static void Main(string[] args)
    {
        CngKeyCreationParameters ckcParams = new CngKeyCreationParameters()
        {
            ExportPolicy = CngExportPolicies.AllowExport,
            KeyCreationOptions = CngKeyCreationOptions.None,
            KeyUsage = CngKeyUsages.AllUsages,                
        };
        ckcParams.Parameters.Add(new CngProperty("Length", BitConverter.GetBytes(2048), CngPropertyOptions.None));

        myCngKey = CngKey.Create(CngAlgorithm.Rsa, "theCngKey", ckcParams);

        byte[] privatePlainTextBlob = myCngKey.Export(CngKeyBlobFormat.Pkcs8PrivateBlob);
 }

Setting the ExportPolicy to AllowPlainTextExport allows the key to be exported, but only in plain text. I would like to create a PCKS8 blob which is encrypted with a symmetric key.

Thanks