Paul - it's actually not that difficult if you have another wheel to copy. I've stripped a few wheels down now, cleaned / polished them and re-built them with new spokes. The trick is to take them 90% built to your LBS and get them to true them for you. Costs a fiver and gets the hard bit done for you. You can also do the carefull lacing bit to avoid scratching the anno on your rims.
Oh, for christ's sake make sure you remove the freewheel before you srtip the back wheel down.....
I'd give it a go if I were you as all you need to do is a bit of trial and error. Most important to note which way the spokes are laced over and under as there is a stronger way to lace them. You'll figure it out mate if you have a wheel to copy next to the one you're building
Spen