I decided to give portableapps a go and downloaded LibreOffice. Install went just fine. All you need to remember is to change the install path so that it points to your USB stick. Have some coffee until install is ready.
Keep in mind LibreOffice driven via USB2.0 is not that fast. However it's very helpful in a situation when no proprietary Office (Microsoft...) is available. So LibreOffice on USB stick is IMO worth trying.
LibreOffice's Writer driven from USB stick