I believe so (I'm not familiar with the Mint installer).
- Back up everything in /home/
- Create a new partition and mount it somewhere under /mnt
- cp -R everything in your /home/<user>/* to /mnt/<user>/. (be sure to include the .* files also)
- During the installation, specify your new partition as /home.
That should do it. From now on, you should just be able to mount that partition under /home whenever re-installing.