This smart card seems to support only 1024 bit key length and certificates in der format with .cer file extension.
Steps to generate and import keys:
1. generate private key and self signed certificate:
openssl req -x509 -nodes -days 3650 -newkey rsa:1024 -keyout privateKey.key -out certificate.crt
2. convert certificate to der format with cer extension
openssl x509 -outform der -in certificate.crt -out certificate.cer
2a. or optionally pack key and certificate in single file
openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt
3. import resulting file/files