I will pretty much tackle anything mechanical and have no worries about an 8V cambelt. But I will admit that my Omega 3.0 V6 got done by the garage so no worries from me about subbing that job out. 2 cams, 2 tensioners and half the engine to remove to get to it... a horrible job and it was money well spent at the time.
Anyway - here is an animation of the 4 stroke cycle that explains TDC. Think about what would happen if the valves open and close at the wrong times in this vid. The worst case is that a valve is still open when the piston reaches TDC. This would (at least) bend the valve.
http://www.youtube.com/watch?v=IYWUWMmimjQ&feature=relatedSince the timing of the valves are tied to the pistons by the cambelt, you can imagine that fitting a cambelt wrongly could have severe consequences... In fact, I think the animation shows the piston clobbering the exhaust valve that failed to close at the end of the cycle (might be my old eyes...)
The Haynes manual will take you through, step by step, how to avoid that and get the timing between the pistons and valves spot on though. If you can follow the video you can understand how important getting the timing right is. The rest of it is just nuts and bolts - no harder than replacing a fan belt or aux belt really.
