keytool -genkeypair \
  -alias testkey \
  -keystore ks.pkcs12 \
  -dname 'CN=TestKey, T=FuncTestCertKey, O=Oracle, OU=JDKSQE, C=US' \
  -storepass passwd \
  -keypass keypasswd \
  -validity 365 \
  -keyalg RSA \
  -keysize 2048 \
  -storetype pkcs12

Warning: Different store and key passwords not supported for PKCS12 KeyStores. Ignoring user-specified -keypass value.

And key password is set to 'passwd'.
KeyStore API allow to create, store & load PKCS12 keystore with different store & key passwords