Hi there,
I am similar to TimTam here... I've got some post-its stuck to my mirror that I read to myself every day (have done since 20wks) - "I hand over control to my body, as I trust it knows what to do" and "I will breath slowly and deeply, allowing my uterus to work effectively" etc etc - these are my positive affirmations. I don't have diagrams or birth positions up - that's quite a good idea though, if that will work for you.
We aren't doing scripts either, nothing "too rehearsed" - would feel weird for us too. I have sat down with my hubby and got some trigger phrases and visualisation (talking about our honeymoon last year) and we've worked on a massage/touch trigger that helps keep me relaxed as well (he strokes my hair or hand on my shoulder). We've also tried to work on "matched breathing" - where he helps me breath slowly and rhymically.
I've got the 'Labour companion' CD too - I find this works for me. And I've the birthing music too - which is great for background to "keep you in the zone"....
My hubby has a list of preferences in terms of environment too - minimum disruption, not much talking, subtle lighting etc.
What works for one might not for another, so you soiund like you are pretty set. Good luck with it lovie xx