Go for it Gav, all you've got to lose is your sanity. Luckily I had already lost most of mine so the rest didn't take long.
Hey Frankie, for measurements from the nut I just used my trusty 600mm steel rule. Getting the measurement down to 3 decimal places is for mugs. All you can do it get it as close as you can. I measured and checked several times. Whether it will be close enough, well I guess time will tell.
Then to prove that I am not a total Ludite, I used my trusty "electronic measuring stick". I measured each fret from the previous one. Its a good way to get peace of mind that the fret spacing is correct. Or at least as correct as I could get it.
Once I was happy that the measurements were OK I then scored the FB with the Stanley knife.
rob