Since someone recently had this problem, here we go. Whenever you only have a .MSI file without a fitting setup.exe or other install tool, either get the MSInstaller from Microsoft.com , and you might be able to just doubleclick and its done, or use the built in proggy by command line parameter.
Its called "msiexec".
I didnt find out much about the usage so far, but obviously -i flag is for isntall, while -d is for deinstall. It also has a r-einstall flag, and iam sure there are more useful commands. Maybe this helps someone sooner or later.
- Gil