I think you might be lucky.. as it's a day's work, if you know what you are doing, probably 2 if not. It's not something you'd choose to do for 'fun'.
I think v8man is pretty much ob the ball with the list of parts, as I'm just in the process of collecting them myself. He did miss tailshaft though, which is an important one (I paid $150 for my manual shaft)
ECU does not have to be changed, but thats been covered. Auto in manual req eCU change, manual into auto not. It will work anyhow, if there are any issues, change it later.
There is some basic wiring you have to do too with neutral switch and a few other things. I don't think you have to change the cluster.. maybe on R33 as it has the christmas tree auto thing in there. but R32 they are exact same (I have two clusters sitting around).
You will need to change your speedo sender too, for the different ratios - or your speedo will be out.
Does anybody know where you can get the selector fork from and boot? From memory it looks very similar to R31 one (nearly identical sized box).. but i didn't get one with my box
For R33 boys you're looking at about $2000 in parts, so it won't be cheap.. There is no place that sells the kits "complete" afaik so you'll have to hunt for a halfcut, wreck, or a wrecker (who will charge you big bickies).
Already for my cheap ass box, and rest of the bits on the R32, it's going to be up around the $1000 mark for the bits.