Sentence:  Set out the ambitions within a realistic time-frame, and re-engineer what you need to achieve in order to get there, taking into account possible interdependencies between different communication elements. This is altogether not very different from any IT project: define your goals, break it into smaller pieces, work out the interdependencies, and <WSD>retro-engineer</WSD> the goals into how you're going to get there. 
Meaning of the word marked with <WSD> tags:  To develop (a process) by starting with the goal and working backwards to determine the steps needed to achieve it.