They do this just to confuse you.

JRMP, or
Java Remote Method Protocol, is the default protocol created by SUN for RMI. In fact you will not even hear SUN refer to JRMP as JRMP. Instead they say the "RMI transport protocol". So basically you do not have to do anything!!!
Use RMI and it will default to JRMP. It is a low level, wire level actually, protocol. By the way there is a JRMP API (net.jini.jrmp).