@Serge, the steps of measuring, cutting then clamping the cables are missing
Did you take pictures??
You did it too fast!
Sorry about that! It was one of those jobs where, once you get started, everything just flows and you don't stop until it's finished.
Not a lot of measuring went on to be honest. I just offered up the cable outers until I was happy with the length (basically the shortest length I could get without kinking and without restricting the turn of the bars), marked it with my thumbnail and cut it. Using a tip from a fellow CCer (whose name currently escapes me, I'll hunt them down for appropriate credit later) I slid the old cable into the new outers before cutting to prevent crushing. I then used my tartar scraper (last seen cleaning the BB threads) to open out the cut ends to prevent any drag.
Then I just popped one end cap (I think that's what they're called) on, slid the cable through, popped the other end cap on (I found it easier to do this than trying to feed the cable through the outer with both end caps in place) and placed in position. Rinse and repeat.
When clamping the cables to the derailleurs you just need to make sure the chain is on the smallest ring and the shifters are in the corresponding gear. Then it's just a case of placing the cable in the clamp and tightening the bolt while maintaining the tension in the cable with your other hand. The barrel adjusters can then be used to adjust the cable tension.
I hope that helps.
Fettling will resume momentarily (once I've polished off a bacon butty).