focus shimmed tappet adjust procedure?

Hi guys, gonna have a go at adjusting the shimmed tappets on my dads 02 1.4 focus. Never done it before but spoke to a few people and gathered a little info, and doesnt sound to hard just time consuming. What i understand is the gap between the top of the valves (shim buckets) and the lobe needs to be set, got sizes at 0.20mm inlet and 0.30mm exhaust. How hard are the shims to remove from the buckets? Is there a special tool for it? A few people have said it can be done by removing rocker cover and prehaps loosening the cams for access, can it be done without removing the cambelt? So does anyone have a step by step procedure for it? The impression i got for this is, rocker cover off, rotate engine to get lobe at tdc then measure gap, and adjust with shim for required gap, this for each valve, inlet and exhaust, does that sound correct? 3 garages have turned the work away saying i wouldnt pay them enough due to the time invovled, so i wouldnt mind trying it. Iam very mechanical minded, and a time served toolmaker, so think iam capable, so anyone have good info to help us with this?