Yep, ended up with this and it works well:
curl -k -X POST -u 'admin:PaSSword' "https://IP_ADDRESS:8443/api/v2/cli/user/call" -H "accept: application/json" -H "Content-Type: application/json" -d '{ "params": [ "-c", "myUsername", "-role", "myRole", "-passwd", "PaSSword!", "-cname", "myName"...