Here is one link I found.
http://tinyurl.com/39tgbl
I'll keep searching for you.
Mainly though, I would say talking with your inner child is like talking to any child you may meet and wish to tell things. It's even better in some ways, because you might know some of the history of your inner child, whereas another might be a total stranger.
Of course, with the DID you need to remember that one of the key issues is safety. All of you needs to hear how safe you are... whenever and wherever you feel safe. That in such and such circumstances, it's also safe to talk. (This has to be based upon your own understandings... safe here at PC, at T's only?)
You can do things with your inner child, for your inner child...and we ALL do this! (Singletons have an inner child too...but we have continuity of communication and understanding what we're doing all the time.) Walt Disney knew and understood the inner child in all of us
So what are some things children need to hear? That they are safe, they're liked, they are a good person and not bad, that they can't have their way all the time but can have some things they ask for and such. Can you think of more?