ejbca: how to generate key pair for client from CA

Question

I'm researching CMP with EJBCA 4.0.12 and ejbca 6 according to rfc 4210, the key pair used for cert can be generated in client RA, CA. My problem here is that when operating with RA mode, then sending a request to CA for certificate requests, I don't know how to generate key pair for that client from CA. Please show me that how I have to do to generate in that case