For anyone interested, I found this guide for making Office 2010 portable using Vmware Thinapp. It seems to be quite an involved process though:
https://www.b4z.co.uk/vmware-thinapp-microsoft-office-2010-setup-guide.html
Since Thinapp is a paid application, there’s an alternative called Evalaze. (Though I’ve read in some places that the free version doesn’t work with Office 2010) The website is no longer available, but thankfully the Wayback Machine has a few copies saved:
https://web.archive.org/web/20150206042614/http://www.evalaze.de/Evalaze/Download/
Alternatively, someone could try to install Office 2010 in Windows XP and then move the files and registry entries to the Windows 2000 installation, though this might really difficult to pull of. I recall reading about a program called TrackWinstall, that analyzes system changes before and after the installation of a program, so maybe something like this could be useful for this purpose.
I think it’s amazing to see this portable copy of Office 2010 running in Windows 2000, but personally, I'd prefer to get the RTM build working as well.