There should be an option during the install to select what partition you want for /, which of course will be formatted, select the partition that has 4.6.1 on it. Then the next option should be to choose a /home partition, choose your current /home, and do not have it formatted.
With every text-based installer that I have used, there at one point or another, you have the option to no format a partition. Just take your time and double check all steps. As well a back-up any critical data.