There is nothing wrong with reading du’a al-qunut from a piece of paper or a booklet in Witr prayer until one is able to memorize it. It is not obligatory for the du’a of Qunut to be in the words narrated from the Prophet.

When Prophet Muhammad (peace and blessings of Allah be upon him) stood up to pray, he used to face the Ka`bah in a standing position, then say ‘Allahu Akbar’, then recite Al-Fatihah, then recite another surah, then make ruku`, then raise up from ruku`, then make sujud, then raise up from sujud, then make a second sujud, then stand up to make the second rak`ah.