The truth of the matter is that they just take time to get used to. I've now used a trackpad for something like 6 straight years, and can therefore use one just as well as a mouse.
I've used a trackpad for 6 months now, and I can tell you that although I'm quite comfortable using the trackpad for regular OS operations, a mouse is simply better and offers more room to move - the trackpad only gives you about 2-3 inches of room for your finger to move.
So although it's fine for normal computer use, I will do just about anything to use a mouse for gaming or anything that requires precision. And I don't think any amount of time can change that.