to be really honest with you, 4 weeks isn't all that long to put a routine together, especially if you want to put it to music. You're going to have to build the routine, that's at least a week's work, practice the routine, another week, find the music and chreograph it and finally put it all together and have a presentable performance.
What music are you going to use? If you're going to be talking over it you'll want to make sure that it's an instrumental and has no lyrics. The words of a song will just be a distraction to what you're saying.
Sorry to sound negative, good luck with it all
