I realize this response is a little bit late, but I didn't know anyone would post to this discussion forum. But hey, here I am now (the author of this module), so I'll still respond to this post in the hopes that someone might find it useful. Oh and hey, I'm monitoring this forum now, so I should be able to answer any questions anyone else might have.
The "intra-process transport" is available as "$rv->processTransport" or "$Tibco::Rv::Transport::PROCESS". It works just like any other transport -- you can send messages, or set up a listener to receive messages via it -- but it has one distinct difference: it only works within the current process. No messages sent via it will go out over the network. So, it is only useful if you want to send a message from one part of your program to another part of the same program. I think it's optimized, so this is more efficient than going out over the network, if you just want to get messages from one part of the program to another.
Also, it is used internally by tibrv to send certain advisory messages. You can set up a listener for these advisory messages, and then respond to them as you see fit. There are quite a few different advisory messages that tibrv might generate, so I didn't bother reproducing them all in my documentation. You'll have to look at the documentation that came with TIB/Rendezvous to see what they all are.