It's quite simple:
msiexec /i build.msi ADDLOCAL=MyFeatureIf you want to install several features, just separate them with commas:
msiexec /i build.msi ADDLOCAL=Website,WebservicesNote that if the features need public properties to be set, then remember to do so, as otherwise it will fail to install, something like this:
msiexec /i build.msi ADDLOCAL=Website SQLSERVERINSTANCE=myinstance
Since I did not want to uninstall and reinstall the relevant features I did another bout of less furious Googling to find out how to remove a particular feature only.
This is somewhat counter-intuitive as you use the install flag:
msiexec /i build.msi REMOVE=Website