If you look, the solution I linked to is Kolusu's
If you start out by thinking that something must have a complicated solution, and that ICETOOL does complicated things, then you will probably end up with something unnecessarily complicated.
The more time you spend thinking about something, the simpler the solution you will come to.
Think of the data, think of the task, think about how you would do it if all you had were pencil and paper. When you become more experienced at it, you'll not need the pencil and paper except for the very complicated things.
Once you know how to do it, how to manipulate the data to get the result you want, then you can start looking at how to do that with a utility/programming language.
If you start the other way round, "complicated things" will indeed turn into "complicated" solutions.