I used a Burda pattern (#9639) which I later found out my sewing teacher does not recommend for beginners. Live and learn. It definitely wasn't easy to follow and I think I will probably go back to drawing up my own pattern based on a good fitting pair of pants.
But all in all I am happy with the end result, as was the little dude. It's hard to find pants that fit him well because he's tall and skinny, so being able to customize them is perfect! These are on the longer side, but I just LOVE that look on little boys.