in LMS 3.x it was possible to start the installation with the "nobackup" option like:
I do not know if this option still exists with the LMS 4.x train but you could give it a try
Assuming you're upgrading on the same host or appliance, you can do a direct upgrade to LMS 4.2 from version 4.1 (or 4.0.1). No backup is necessary - your configuration and any data will migrate directly. (Reference)
Of course you can always do a fresh install and rebuild from scratch too.
Marvin, you are correct, a direct upgrade does not need a backup to get back all your data, but I think the installation process does a backup automatically - at least this was the case last week, when I performed an upgrade on a windows machine (from LMS 4.1 > LMS 4.2) and I assume that's what Elisabeth wants to avoid.
In any case, disable any anti-virus software during the upgrade procedure. This will speed up the installation and also prevents any failures caused by AV software.